Aqueous polyester coating compositions

ABSTRACT

An aqueous coating composition comprising a crosslinkable water-dispersible polyester oligomer wherein said composition when drying to form a coating has the following properties: an open time of at least 20 minutes, a wet edge time of at least 10 minutes, a thumb hard time of ≦48 hours and a tack-free time ≦20 hours and an equilibrium viscosity of ≦5000 Pa.s at any solids content when drying in the range of from 20 to 55 wt % using a shear rate in the range of from 9±0.5 to 90±5 s −1  and at 23±2° C.

[0001] The present invention relates to certain aqueous ambienttemperature crosslinkable and shelf stable polyester polymercompositions which, inter alia, provide coatings having improved openand wet edge times as well as good tack-free times.

[0002] A general need when applying a decorative or protective coatingto a substrate is to be able to repair irregularities in the still-wetcoating after some time has elapsed, for example by re-brushing over afreshly coated wet substrate, or by applying more of the coatingcomposition over a previously coated substrate either over the main areaof the coating or an edge of the coating or even blending a drop intothe coating without vitiating the complete merging of any boundaries inthe vicinity of the repaired irregularity. Traditionally compositionscontaining binder polymers dissolved in organic solvents are used andthe organic solvents are employed to modify the drying characteristicsof the coated composition. For example, organic solvent based alkydswith an open time of 30 to 45 minutes are available in the decorative“Do-it-yourself” DIY market. However the disadvantage of organic solventbased coatings is the toxic and flammable nature of such solvents andthe pollution and odour caused on evaporation as well as the relativelyhigh cost of organic solvents.

[0003] Thus with the continuing concern about the use of organic solventbased coating compositions there has been a long felt need for anaqueous coating composition with comparable properties to thoseachievable using organic solvent based compositions. Unfortunately,aqueous polymer coating compositions currently known to the art do notoffer a combination of drying properties which would make them fullycomparable (or even superior to) solvent-based coatings, and inparticular do not provide desirably long open and wet edge times (asdiscussed above and also later) together with desirably short tack-freetimes (discussed later).

[0004] Thus, very commonly, aqueous-based polymer coating compositionsemploy dispersed high molecular weight polymers as the binder materialsthereof. This results in, inter alia, a short wet edge time when thecoating composition is dried because the dispersed polymer particlestend to coalesce in the edge region of an applied coating very soonafter a wet coating has been applied (probably due to the maximumpacking fraction of the polymer particles having been reached) to form acontinuous film, and since the polymer of this film is of high viscositybecause of its high molecular weight, the lapping (i.e. wet edge) timeof the composition is poor.

[0005] It has been shown by viscosity measurements taken during dryingthat existing alkyd emulsions have a high viscosity phase inversion peakduring drying. (Phase inversion is defined as the transition from abinder in a continuous water phase to water in a continuous binder phasewhich occurs during drying). The consequence is a difficulty inre-brushing which starts a few minutes after application of the coating.

[0006] It is known from the prior art that longer wet edge or open timeis achievable by using solution-type aqueous oligomers (U.S. Pat. No.4,552,908) which can be diluted with large amounts of organic solvent(s)in order to create a low viscosity continuous phase during drying of thefilm. However, these systems have high Volatile Organic Contents (VOC's)and are generally unacceptably water-sensitive.

[0007] Open time can also be prolonged by using evaporation suppressants(such as e.g. eicosanol), as described in for example EP 210747.However, water sensitivity is also a problem in this case. Moreover, thewet edge open time is insufficiently improved by using such evaporationsuppressants.

[0008] From the literature it is also known that open time is easilyprolonged by using low solids contents in the aqueous polymercompositions, but this generally results in the need to apply manylayers of paint (for good opacity). In addition, the wet edge time isgenerally only moderately influenced by reducing the solids content ofan aqueous coating composition with water.

[0009] Longer times for repairing irregularities can be achieved byemploying aqueous coating compositions in which the binder polymers havevery low viscosities. However, hitherto, a problem with such lowviscosity polymer binders, is that the resultant coatings have a slowdrying rate, resulting in the coating remaining tacky for anunacceptably long time. A coating should also preferably drysufficiently quickly to avoid the adherence of dust and to ensure thatthe coating quickly becomes waterproof (in case of outdoorapplications), and as discussed above quickly becomes tack-free andsufficiently hard.

[0010] Indeed, the difficulty in developing aqueous polymer coatingcompositions having a desirable combination of drying properties whencoated onto a substrate has been particularly discussed in a recentinterview given by Professor Rob van der Linde (Professor of CoatingsTechnology, University of Technology, Eindhoven, NL) and Kees van derKolk (Sigma Coatings) and reported in “Intermediair” 10.06.1999, 35(23),pages 27-29. In this interview, concerning environmentally friendlypaints, there is described the problem of applying aqueous paints whereeven the professional painter has little enough time to correct anyirregularities when needed. This is contrasted (in the interview) withsolvent-based paints (e.g. alkyd paints) which are workable for a muchlonger time but have the disadvantage that the organic solvents, forminga major component of such compositions, are toxic and expensive. Theinterview also mentions that in the coming years, three universitieswill cooperate in a project to overcome the drying disadvantages ofaqueous paints. Thus this interview emphasises the current andcontinuing need and desirability for achieving aqueous polymer coatingscompositions having improved drying. properties.

[0011] The open time for a coating composition is, in brief, the periodof time that the main area (the bulk) of an applied aqueous coatingremains workable after it has been applied to a substrate, in the sensethat during this period re-brushing or application of more coating overthe main area of a freshly coated wet substrate is possible withoutcausing defects such as brush marks in the final dried coating. (A moreformal definition of open time is provided later in this specification).

[0012] The wet edge time for a coating composition is the period of timethat the edge region of an applied aqueous coating remains workableafter it has been applied to a substrate, in the sense that during thisperiod re-brushing or application of more coating over the edge regionof a freshly coated wet substrate is possible without causing defectssuch as lap lines in the final dried coating. (A more formal definitionof wet edge time is provided later in this specification).

[0013] U.S. Pat. No.4,552,908 describes a solids/viscosity relationshipof oligomers with defined molecular weight upon drying coatings appliedfrom compositions containing the oligomers. The compositions have >10minutes wet edge time, but there is no mention that the oligomers arecrosslinkable (an important feature of the present invention—see later).All oligomers mentioned in the patent are very water-sensitive.

[0014] WO 97/26303 discloses a water-borne hybrid composition comprisingan emulsifiable resin, an aqueous polymer dispersion and surfactantwhere the composition has a dry solids content of 60 to 90% by weight.However no drying properties are exemplified or described.

[0015] WO 00/24837 discloses a polyurethane/acrylate dispersion blendedwith a polyurethane with oxidatively drying groups; however the maximumopen time was only 7 minutes, and, in particular, a wet edge time ofonly 4 minutes was achieved, neither of which is sufficient for mostdecorative purposes.

[0016] U.S. Pat. No.4,346,044 discloses water-soluble air drying alkyds,however a high solvent content is required and no drying properties areexemplified.

[0017] We have now invented aqueous polymer coating compositions havinga very advantageous combination of drying properties, particularly withregard to open time and tack-free time as discussed above, and which(surprisingly in view of the comments by van der Linde and van der Kolk)avoid the drawbacks of the currently available compositions.

[0018] According to the present invention there is provided an aqueouscoating composition comprising a crosslinkable water-dispersiblepolyester oligomer(s) wherein said composition when drying to form acoating has the following properties:

[0019] i) an open time of at least 20 minutes;

[0020] ii) a wet-edge time of at least 10 minutes;

[0021] iii) a thumb hard time of ≦48 hours;

[0022] iv) a tack-free time of ≦20 hours;

[0023] v) 0 to 25% of co-solvent by weight of the composition; and

[0024] vi) an equilibrium viscosity of ≦5,000 Pa.s, at any solidscontent when drying in the range of from 20 to 55% by weight of thecomposition, using any shear rate in the range of from 9±0.5 s⁻¹ to 90±5s⁻¹ and at 23±2° C.

[0025] Open time is more formally defined as the maximum length of time,using the test method, under the specified conditions described herein,in which a brush carrying the aqueous composition of the invention canbe applied to the main area of a coating of the aqueous composition ofthe invention after which the coating flows back so as to result in ahomogenous film layer.

[0026] Preferably the open time is at least 25 minutes, more preferablyat least 30 minutes and most preferably at least 35 minutes.

[0027] Wet edge time is more formally defined as the maximum length oftime, using the test method, under the specified conditions describedherein, in which a brush carrying the aqueous composition of theinvention can be applied to the edge region of a coating of the aqueouscomposition of the invention after which the coating flows back withoutleaving any lap lines so as to result in a homogenous film layer.

[0028] Preferably the wet-edge time is at least 12 minutes, morepreferably at least 15 minutes and especially at least 25 minutes.

[0029] The drying process can be divided in four stages namely theperiod of time necessary to achieve dust-free, tack-free, sandable andthumb-hard coatings using the tests described herein.

[0030] Preferably the dust free time is ≦4 hours, more preferably ≦2hours and most preferably ≦50 minutes.

[0031] Preferably the tack-free time is ≦15 hours, preferably ≦12 hours,more preferably ≦10 hours and most preferably ≦8 hours.

[0032] Preferably the thumb hard time is ≦24 hours, most preferably ≦16hours and especially ≦10 hours.

[0033] Preferably the resultant coating is sandable within 72 hours,more preferably within 48 hours, still more preferably within 24 hours,and especially within 16 hours.

[0034] A co-solvent as is well known in the coating art, is an organicsolvent employed in an aqueous composition to improve the dryingcharacteristics thereof.

[0035] The co-solvent may be solvent incorporated or used duringpreparation of the polyester oligomer(s) or may have been added duringformulation of the aqueous composition.

[0036] The equilibrium viscosity of the aqueous coating composition whenmeasured under the conditions as described above, is a suitable methodfor illustrating the drying characteristics of the aqueous coatingcomposition. By the equilibrium viscosity of an aqueous composition at aparticular shear rate and solids content is meant the viscosity measuredwhen the aqueous composition has been subjected to the shear rate at forlong enough to ensure that the viscosity measurement has reached aconstant value.

[0037] If the composition is to remain brushable and workable duringdrying so that it has the desired open time and wet edge time, it isnecessary that its equilibrium viscosity does not exceed defined limitsduring the drying process and hence over a range of solids contents.Accordingly the crosslinkable water-dispersible polyester oligomer(s)which are used in this invention do not give a significant phaseinversion viscosity peak, if any at all, during the drying process whenthe system inverts from one in which water is the continuous phase toone in which the crosslinkable water-dispersible polyester oligomer(s)is the continuous phase.

[0038] The shear rate to measure the equilibrium viscosity is preferablyany shear rate in the range of from 0.9±0.05 to 90±5s⁻¹, more preferablyany shear rate in the range of from 0.09±0.005 to 90±5s⁻¹.

[0039] Preferably the equilibrium viscosity of the aqueous coatingcomposition of the invention is ≦3000 Pa.s, more preferably ≦1500 Pa.s,still more preferably ≦500 Pa.s, especially ≦100 Pa.s and mostespecially ≦50 Pa.s when measured as defined above.

[0040] Preferably, the composition of the invention has an equilibriumviscosity ≦5,000 Pa.s when measured using any shear rate in the range offrom 0.09±0.005 to 90±5 s⁻¹, and an equilibrium viscosity of ≦3,000 Pa.swhen measured using any shear rate in the is range of from 0.9±0.05 to90±5 s⁻¹, and an equilibrium viscosity of ≦1,500 Pa.s when measuredusing any shear rate in the range of from 9±0.5 to 90±5 s⁻¹, at anysolids content when drying in the range of from 20 to 55% by weight ofthe composition and at 23±2° C.

[0041] More preferably, the composition of the invention has anequilibrium viscosity of ≦3,000 Pa.s when measured using any shear ratein the range of from 0.09±0.005 to 90±5 s⁻¹, and an equilibriumviscosity of ≦1,500 Pa.s when measured using any shear rate in the rangeof from 0.9±0.05 to 90±5 s³¹ ¹, and an equilibrium viscosity of ≦500Pa.s when measured using any shear rate in the range of from 9±0.5 to90±5 s⁻¹, at any solids content when drying in the range of from 20 to55% by weight of the composition and at 23±2° C.

[0042] Most preferably, the composition of the invention has anequilibrium viscosity of ≦1500 Pa.s when measured using any shear ratein the range of from 0.09±0.005 to 90±5 s⁻¹, and an equilibriumviscosity of ≦200 Pa.s when measured using any shear rate in the rangeof from 0.9±0.05 to 90±5 s⁻¹, and an equilibrium viscosity of ≦100 Pa.swhen measured using any shear rate in the range of from 9±0.5 to 90±5s⁻¹, at any solids content when drying in the range of from 20 to 55% byweight of the composition and at 23±2° C.

[0043] Preferably the equilibrium viscosity of the composition of theinvention is ≦5000 Pa.s, more preferably ≦3000 Pa.s when measured usingany shear rate in the range of from 0.9±0.05 to 90±5s⁻¹, more preferablyusing any shear rate in the range of from 0.09±0.005 to 90±5s³¹ ¹, aftera 12%, preferably a 15% and most preferably a 18% increase in the solidscontent by weight of the composition.

[0044] A 12% increase in the solids content by weight of the compositionmeans for example going from a solids content of 35 to 47% by weight ofthe composition.

[0045] Preferably the solids content of the aqueous coating compositionwhen determining the equilibrium viscosity is in the range of from 20 to60%, more preferably in the range of from 20 to 65%, most preferably inthe range of from 20 to 70%, especially in the range of from 20 to 75%.

[0046] In a preferred embodiment of the present invention said polyesteroligomer(s) has a solution viscosity ≦150 Pa.s, as determined from a 80%by weight solids solution of the crosslinkable polyester oligomer(s) inat least one of the solvents selected from the group consisting ofN-methylpyrrolidone, n-butylglycol and mixtures thereof, at a shear rateof 90±5 s⁻¹ and at 50±2° C.

[0047] A choice of solvents for determining the solution viscosity ofthe polyester oligomer(s) is provided herein because the nature of thepolyester oligomer(s) may affect their solubility.

[0048] Preferably the solution viscosity of the crosslinkable polyesteroligomer(s) is ≦100 Pa.s, more especially ≦50 Pa.s and most especially≦20 Pa.s when measured as defined above.

[0049] Alternatively, and more preferably, the solution viscosity of thepolyester oligomer(s) may be measured at 23±2° C. and the crosslinkablepolyester oligomer(s) may thus also be described as preferably having asolution viscosity ≦250 Pa.s, as determined from a 70% by weight solidssolution of the crosslinkable polyester oligomer(s) in a solvent mixtureconsisting of:

[0050] i) at least one of the solvents selected from the groupconsisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof;

[0051] ii) water and

[0052] iii) N,N-dimethylethanolamine;

[0053] where i), ii) and iii) are in weight ratios of 20/7/3respectively, using a shear rate of 90±5 s⁻¹ and at 23±2° C.

[0054] Preferably in the preceding alternative the solution viscosity ofthe crosslinkable polyester oligomer(s) is ≦100 Pa.s, more especially≦50 Pa.s and most especially ≦20 Pa.s when measured as defined herein at23±2° C.

[0055] If a mixture of N-methylpyrrolidone (NMP) and n-butylglycol (BG)is used, preferably the ratio of NMP:BG is in the range of from0.01:99.9 to 99.9:0.01, more preferably the ratio of NMP:BG is in therange of from 0.01:99.9 to 10:90 and in the range of from 90:10 to99.9:0.01, and most preferably the ratio of NMP:BG is in the range offrom 0.5:99.5 to 5:95 and in the range of from 95:5 to 99.5:0.5.

[0056] In a special embodiment of the present invention the wet edgetime in minutes of the aqueous coating composition is at least Q/(wt. %solids of the aqueous coating composition)^(0.5), wherein the solidscontent of the aqueous coating composition is between 15 and 70 wt. %,more preferably between 30 and 65 wt. % and most preferably between 40and 60 wt. % and Q is a constant of 84, more preferably of 100, mostpreferably of 126 and especially of 151.

[0057] The crosslinkable polyester oligomer(s) may crosslink at ambienttemperature by a number of mechanisms including but not limited toautoxidation, Schiff base crosslinking and silane condensation. Bycrosslinking by autoxidation is meant that crosslinking results from aoxidation occurring in the presence of air and usually involves a freeradical mechanism and is preferably metal-catalysed resulting incovalent crosslinks. By Schiff base crosslinking is meant thatcrosslinking takes place by the reaction of a carbonyl functionalgroup(s), where by a carbonyl functional group herein is mean an aldo orketo group and including an enolic carbonyl group such as is found in anacetoacetyl group, with a carbonyl-reactive amine and/or hydrazine (orblocked amine and/or blocked hydrazine) functional group. Examples ofcarbonyl-reactive amine (or blocked amine) functional groups includeones provided by the following compounds or groups: R—NH₂, R—O—NH₂,R—O—N═C<, R—NH—C(═O)—O—N═C< and R—NH—C(═O)—O—NH₂ where R is optionallysubstituted C₁ to C₁₅, preferably C₁ to C₁₀ alkylene, optionallysubstituted alicyclic or optionally substituted aryl, or R may also bepart of a polymer. Examples of carbonyl-reactive hydrazine (or blockedhydrazine) compounds or groups include R—NH—NH₂, R—C(═O)—NH—NH₂,R—C(═O)—NH—N═C<, R—NH—C(═O)—NH—NH₂ and R—NH—C(═O)—NH—N═C< where R is asdescribed above. By silane condensation is meant the reaction of alkoxysilane or —SiOH groups in the presence of water, to give siloxane bondsby the elimination of water and/or alkanols (for example methanol)during the drying of the aqueous coating composition.

[0058] Preferably the crosslinkable polyester oligomer(s) is aself-crosslinkable polyester oligomer(s) (i.e. crosslinkable without therequirement for added compounds which react with groups on the polyesteroligomer(s) to achieve crosslinking, although these can still beemployed if desired). Preferably the crosslinking is by autoxidation,optionally in combination with other crosslinking mechanisms asdiscussed herein. Suitably autoxidation is provided for example by fattyacid groups containing unsaturated bonds (by which is meant the residueof such fatty acids which have become incorporated into the polyesteroligomer(s) by reaction with their carboxyl groups) or by (meth)allylfunctional residues, -keto ester groups or β-keto amide groups.Preferably autoxidation is provided at least by fatty acid groupscontaining unsaturated bonds.

[0059] Preferably the concentration of unsaturated fatty acid groups ifpresent in the autoxidisably crosslinkable polyester oligomer(s) is 10to 80%, more preferably 12 to 70%, most preferably 15 to 60% by weightbased on the weight of the polyester oligomer(s). If combined with otherautoxidisable groups in the aqueous coating composition, the fatty acidcontent may be below 10% by weight of the polyester oligomer(s). For thepurpose of determining the fatty acid group content of the polyesteroligomer(s), it is convenient for practical purposes to use the weightof the fatty acid reactant including the carbonyl group but excludingthe hydroxyl group of the terminal acid group of the fatty acid.Suitable unsaturated fatty acids for providing fatty acid groups in theoligomer(s) include fatty acids derived from vegetable oil andnon-vegetable oil such as soyabean oil, palm oil, linseed oil, tung oil,rapeseed oil, sunflower oil, tallow oil, (dehydrated) castor oil,safflower oil and fatty acids such as linoleic acid, linolenic acid,palmitoleic acid, oleic acid, eleostearic acid, licanic acid,arachidonic acid, ricinoleic acid, erucic acid, gadoleic acid,clupanadonic acid and/or combinations thereof. Particularly preferred isa polyester oligomer(s) in which the autoxidisable groups are onlyderived from unsaturated fatty acids. Preferably at least 40% by weight,more preferably at least 60% by weight, of the unsaturated fatty acidgroups contain at least two unsaturated groups.

[0060] Other crosslinking mechanisms known in the art include thereaction of epoxy groups with amino, carboxylic acid or mercapto groups,the reaction of amine or mercapto groups with ethylenically unsaturatedgroups such as fumarate and acryloyl groups, the reaction of maskedepoxy groups with amino or mercapto groups, the reaction ofisothiocyanates with amines, alcohols or hydrazines, the reaction ofamines (for example ethylene diamine or multifunctional amine terminatedpolyalkylene oxides) with -diketo (for example acetoacetoxy oracetoamide) groups to form enamines. The use of blocked crosslinkinggroups may be beneficial.

[0061] The crosslinkable polyester oligomer(s) may be completelywater-soluble (which is less preferred) or only have partial solubilityin water. If the crosslinkable polyester oligomer(s) is only partiallysoluble the crosslinkable polyester oligomer(s) preferably has low watersolubility in a pH range of from 2 to 10 and is eitherself-water-dispersible (i.e. dispersible by virtue of a sufficientconcentration of selected bound (in-chain, chain-pendant and/orchain-terminal) hydrophilic groups built into the crosslinkablepolyester oligomer(s), and thus not requiring high shear techniquesand/or added surfactants to produce the dispersion, although suchmethods can also be included if desired), or is only dispersible inwater with the aid of added (i.e. external) surface active agents and/oruse of high shear mixing. Low water solubility confers the advantage ofa reduced water-sensitivity of the applied coating to water. Such lowwater solubility is defined herein as the crosslinkable polyesteroligomer(s) being less than 80% by weight soluble in water throughoutthe pH range of from 2 to 10 as determined by a centrifuge test asdescribed herein. Preferably the crosslinkable polyester oligomer(s) is≦50% most preferably ≦30% by weight soluble in water throughout the pHrange of from 2 to 10.

[0062] The crosslinkable polyester oligomer(s) preferably contains asufficient concentration of bound hydrophilic water-dispersing groupscapable of rendering the oligomer self water-dispersible, but theconcentration of such groups is preferably not so great that theoligomer has an unacceptably high water solubility in order to notcompromise the water sensitivity of the final coating.

[0063] The type of hydrophilic groups capable of rendering thecrosslinkable polyester oligomer(s) water-dispersible are well known inthe art, and can be ionic water-dispersing groups or non-ionicwater-dispersing groups. Preferred non-ionic water-dispersing groups arepolyalkylene oxide groups, more preferably polyethylene oxide groups. Asmall segment of the polyethylene oxide group can be replaced bypropylene oxide segment(s) and/or butylene oxide segment(s), however thepolyethylene oxide group should still contain ethylene oxide as a majorcomponent. When the water-dispersible group is polyethylene oxide, thepreferred ethylene oxide chain length is >4 ethylene oxide units,preferably >8 ethylene oxide units and most preferably >15 ethyleneoxide units. Preferably the polyester oligomer(s) have a polyethyleneoxide content of 0 to 50% by weight, more preferably 0 to 45% by weight,still more preferably 0 to 38% by weight, especially 3 to 35% by weightand most preferably 5 to 25% by weight. Preferably the polyethyleneoxide group has a Mw from 175 to 5000 Daltons, more preferably from 350to 2200 Daltons , most preferably from 660 to 2200 Daltons.

[0064] Preferred ionic water-dispersing groups are anionicwater-dispersing groups, especially carboxylic, phosphonic and orsulphonic acid groups. The anionic water-dispersing groups arepreferably fully or partially in the form of a salt. Conversion to thesalt form is optionally effected by neutralisation of the crosslinkablepolyester oligomer(s) with a base, preferably during the preparation ofthe crosslinkable polyester oligomer(s) and/or during the preparation ofthe composition of the present invention. The anionic dispersing groupsmay in some cases be provided by the use of a monomer having an alreadyneutralised acid group in the polyester oligomer(s) synthesis so thatsubsequent neutralisation is unnecessary. If anionic water-dispersinggroups are used in combination with a non-ionic water-dispersing group,neutralisation may not be required.

[0065] If the anionic water-dispersing groups are neutralised, the baseused to neutralise the groups is preferably ammonia, an amine or aninorganic base. Suitable amines include tertiary amines, for exampletriethylamine or N,N-dimethylethanolamine. Suitable inorganic basesinclude alkali hydroxides and carbonates, for example lithium hydroxide,sodium hydroxide, or potassium hydroxide. A quaternary ammoniumhydroxide, for example N⁺(CH₃)₄OH⁻, can also be used. Generally a baseis used which gives the required counter ion desired for thecomposition. For example, preferred counter ions include Li⁺, Na⁺, K⁺,NH₄ ⁺ and substituted ammonium salts.

[0066] Cationic water dispersible groups can also be used, but are lesspreferred. Examples include pyridine groups, imidazole groups and orquaternary ammonium groups which may be neutralised or permanentlyionised (for example with dimethylsulphate).

[0067] The crosslinkable polyester oligomer(s) preferably has a weightaverage molecular weight (Mw) in the range of from 1000 to 100,000Daltons, preferably in the range of from 1000 to 80,000 Daltons, morepreferably in the range of from 1000 to 50,000 Daltons, most preferablyin the range of from 1000 to 20,000 Daltons. For the purpose of thisinvention any molecular species mentioned herein with a Mw <1000 Daltonsis classified as either a reactive diluent or a plasticiser and istherefore not taken into account for the determination of the Mw, Mn andPDi. When Daltons are used to give molecular weight data, it should beunderstood that this is not a true molecular weight but a molecularweight measured against polystyrene standards.

[0068] Preferably a significant part of any crosslinking reaction onlytakes place after application of the aqueous coating composition to asubstrate, to avoid an excessive molecular weight build up which maylead to an increased viscosity of the aqueous coating composition on thesubstrate in the early stages of drying.

[0069] The molecular weight limits suitable to obtain the preferred lowsolution viscosity of the crosslinkable polyester oligomer(s) as definedabove may depend in part on the amount and type of co-solvent present inthe aqueous composition of the invention, where a higher molecularweight limit is possible when there is more co-solvent in thecomposition, and the lower molecular weight preferences are moreapplicable to low or zero co-solvent concentrations.

[0070] The molecular weight distribution (MWD) of the crosslinkablepolyester oligomer(s) has an influence on the equilibrium viscosity ofthe aqueous composition of the invention and hence an influence on theopen time. MWD is conventionally described by the polydispersity index(PDi). PDi is defined as the weight average molecular weight divided bythe number average molecular weight (Mw/Mn) where lower values areequivalent to lower PDi's. It has been found that a lower PDi oftenresults in lower viscosities for a given Mw crosslinkable polyesteroligomer(s). Preferably the value of PDi is ≦30, more preferably ≦15,still more preferably ≦10 and most preferably ≦5. In a preferredembodiment the value of Mw×Pdi^(0.8) of the crosslinkable polyesteroligomer(s) is ≦550,000, more preferably the Mw×PDi^(0.8) is ≦400,000,still more preferably the Mw×PDi^(0.8) is ≦300,000 and most preferablythe Mw×PDi^(0.8) is ≦220,000.

[0071] The crosslinkable polyester oligomer(s) may comprise a singlecrosslinkable polyester oligomer(s) or a mixture of polyesteroligomer(s). The crosslinkable polyester oligomer(s) may optionally beused in conjunction with crosslinkable oligomer(s) of a non-polyestertype which has a solution viscosity within the same preferred limits asthe solution viscosity of the polyester oligomer(s). Indeed up to 90% byweight of crosslinkable oligomers in the invention composition may be ofa non-polyester type. The crosslinkable oligomer(s) (polyester typeplus, if present, non-polyester type) may optionally be used inconjunction with up to 250% by weight thereof of any type ofnon-crosslinkable oligomer (i.e. polyester and/or non-polyester type)provided that the non-crosslinkable oligomer(s) has a solution viscositywithin the preferred ranges defined above (for the crosslinkablepolyester oligomer(s)). In such cases, more preferably up to 120 wt. %of the non-crosslinkable oligomer(s) (based on the weight ofcrosslinkable oligomer(s) is used, still more preferably up to 70 wt. %,especially up to 30 wt. %, more especially up to 10 wt. %, and mostpreferably 0%. Oligomer(s) of a non polyester type include but are notlimited to for example vinyl oligomer(s), polyamide oligomer(s),polyether oligomer(s), polycarbonate oligomer(s), polysiloxaneoligomer(s) and/or polyurethane oligomer(s) and the non-polyester typeoligomer(s) may optionally be branched.

[0072] The crosslinkable polyester oligomer(s) can be prepared usingconventional polymerisation procedures known to be effective forpolyester synthesis. General processes for the preparation of alkydpolyesters are described in “Alkyd Resin Technology” by T C Patton,Publisher John Wiley & sons Inc. (1962). General methods for preparingcrosslinkable polyesters are also disclosed in EP 486092, U.S. Pat.No.3,494,882, U.S. Pat. No.4,251,406, EP 0000087, WO 95/02019, U.S. Pat.No.5,378,757 and GB 2306489. Thus, it is well known that polyesters,which contain carbonyloxy (i.e. —C(═O)—O—) linking groups may beprepared by a condensation polymerisation process in which monomer(s)providing an “acid component” (including ester-forming derivativesthereof) is reacted with monomer(s) providing a “hydroxyl component”.The monomer(s) providing an acid component may be is selected from oneor more polybasic carboxylic acids such as di- or tri-carboxylic acidsor ester-forming derivatives thereof such as acid halides, anhydrides oresters. The monomer(s) providing a hydroxyl component may be one or morepolyhydric alcohols or phenols (polyols) such as diols, triols, etc.Mono-functional acid and hydroxy components may also be included in thepreparation of the crosslinkable polyester oligomer(s). (It is to beunderstood, however, that the polyester oligomer(s) may contain, ifdesired, a proportion of carbonylamino linking groups —C(=O)—NH— (i.e.amide linking group) by including an appropriate amino functionalreactant as part of the “hydroxyl component” or alternatively all of thehydroxyl component may comprise amino functional reactants, thusresulting in a polyamide oligomer; such amide linkages are in factuseful in that they are more hydrolysis resistant.) The reaction to forma polyester oligomer(s) may be conducted in one or more stages (as iswell known). It would also be possible to introduce in-chainunsaturation into the polyester oligomer(s) by e.g. employing as part ofthe monomer(s) providing an acid component an olefinically unsaturateddicarboxylic acid or anhydride.

[0073] There are many examples of carboxylic acids (or their esterforming derivatives) which can be used in polyester oligomer(s)synthesis for the provision of the monomer(s) providing an acidcomponent. Examples include, but are not limited to monofunctional acidssuch as (alkylated) benzoic acid and hexanoic acid; and C₄ to C₂₀aliphatic, alicyclic and aromatic dicarboxylic acids (or higherfunctionality acids) or their ester-forming derivatives (such asanhydrides, acid chlorides, or lower alkyl esters). Specific examplesinclude adipic acid, fumaric acid, maleic acid, succinic acid, itaconicacid, azeleic acid, sebacic acid, nonanedioic acid, decanedioic acid,1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,1,2-cyclohexanedicarboxylic acid, terephthalic acid, fatty acid dimers,isophthalic acid, 5-sodiosulpho isophthalic acid, phthalic acid andtetrahydrophthalic acid. Anhydrides include succinic, maleic, phthalic,trimellitic and hexahydrophthalic anhydrides.

[0074] Similarly there are many examples of polyols which may be used inpolyester oligomer(s) synthesis for the provision of the monomer(s)providing a hydroxyl component. The polyol(s) preferably have from 1 to6 (more preferably 2 to 4) hydroxyl groups per molecule. Suitablemonofunctional alcohols include for example eicosanol and laurylalcohol. Suitable polyols with two hydroxy groups per molecule includediols such as 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol,1,6-hexanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), the1,2-, 1,3- and 1,4-cyclohexanediols and the corresponding cyclohexanedimethanols, diethylene glycol, dipropylene glycol, and diols such asalkoxylated bisphenol A products, e.g. ethoxylated or propoxylatedbisphenol A. Suitable polyols with three hydroxy groups per moleculeinclude triols such as trimethylolpropane (TMP) and 1,1,1-tris(hydroxymethyl)ethane (TME). Suitable polyols with four or more hydroxygroups per molecule include bis-TMP, pentaerythritol(2,2-bis(hydroxymethyl)-1,3-propanediol), bis-pentaerythritol andsorbitol (1,2,3,4,5,6-hexahydroxyhexane).

[0075] The crosslinker groups may be introduced into the polyesteroligomer(s) using two general methods: i) by utilising in thepolymerisation process to form a polyester oligomer(s) monomer(s)providing at least part of the acid or hydroxyl components which carry acrosslinker group; or ii) utilising monomer(s) providing at least partof the acid or hydroxyl components which bears selected reactive groupsand which monomer(s) is subsequently reacted with a compound carrying acrosslinker group and also a reactive group of the type which will reactwith the selected reactive groups on the monomer to provide attachmentof the crosslinker group to the polyester oligomer(s) via covalentbonding.

[0076] To prepare autoxidisably crosslinkable polyester oligomer(s)preferably a monomer providing an acid or a hydroxyl component bearingan unsaturated fatty acid group(s) as crosslinker group(s) may be usedin the polyester oligomer(s) synthesis.

[0077] Hydrophilic water-dispersing groups (or groups which may besubsequently converted to such water-dispersing groups) are optionallyintroduced into the polyester oligomer(s) using two general methods: i)by utilising in the polymerisation process to form a polyesteroligomer(s) monomer(s) providing part of the acid or hydroxyl componentwhich carry a hydrophilic water-dispersing group; or ii) utilisingmonomer(s) providing part of the acid or a hydroxyl component whichbears selected reactive groups and which monomer is subsequently reactedwith a compound carrying a hydrophilic water-dispersing group and also areactive group of the type which will react with the selected reactivegroups on the monomer to provide attachment of the hydrophilicwater-dispersing group to the polyester oligomer(s) via covalentbonding.

[0078] The hydrophilic water-dispersing groups if present, should bepresent in sufficient level in the polyester oligomer(s) to impartwater-dispersibility thereto. Suitable non-ionic hydrophilic waterdispersing groups include for example ethylene oxide-containing hydroxyfunctional compounds such as alkoxypolyethlene glycols and polyethyleneglycols. Preferably the hydrophilic water-dispersing groups arecarboxylic acid groups, sulphonic acid groups or sulphonate anion groups(neutralisation of the sulphonic acid groups preferably already havingbeen effected in the monomer). Preferably incorporation of carboxylicacid groups can occur by having a residual carboxylic acidfunctionality, post functionalisation of hydroxy-functionalisedpolyester oligomer(s) or use of sterically hindered hydroxy functionalacids such as dimethylolpropionic acid. Preferably, the sulphonic acidor sulphonate anion containing monomer is a dicarboxylic acid monomerhaving at least one sulphonic acid salt group substituent.Alternatively, alkyl ester groups may be used in place of the carboxylicacid groups. Such a monomer will therefore be part of the acid componentused in the polyester synthesis. Examples of such compounds are thealkali metal salts of sulphonic acid substituted aromatic dicarboxylicacids, for example alkali metal salts of 5-sulpho-1,3-benzenedicarboxylic acid. Particularly preferred is sodio-5-sulphoisophthalicacid (SSIPA). Other useful sulphonic acid containing monomers are thealkali metal salts of sulphonic acid substituted aromatic dicarboxylicacid-dihydroxyalkylesters such as the alkali metal salts of5-sulpho-1,3-benzenedicarboxylic acid -1 ,3-bis(2-hydroxyethyl)ester.

[0079] Preferably the ionic sulphonate water-dispersing group content ofthe polyester oligomer(s) is in the range of from 7.5 to 100milliequivalents of ionic water-dispersing groups per 100 g of polyesteroligomer(s), more preferably from 10 to 75 milliequivalents per 100 g.Preferably the acid value of the polyester oligomer(s) is in the rangeof from 0 to 150 mgKOH/g, more preferably in the range of from 0 to 120mgKOH/g, especially in the range of from 5 to 90 mgKOH/g, moreespecially in the range of from 10 to 60 mgKOH/g and most especially inthe range of from 10 to 40 mgKOH/g.

[0080] If the polyester oligomer(s) is prepared using monomer(s)providing acid or hydroxyl component which have an unsaturated group(s),the polyester oligomer(s) will have un-saturation incorporated into itsstructure, and can if desired be subjected to a further stage ofpolymerisation by a free radical mechanism, to cause chain-extension ofthe polyester and such a reaction would usually take place in an aqueousdispersion phase, rather than in the melt as when conducting theesterification polymerisation process. Alternatively the unsaturatedgroup in the polyester oligomer(s) may be utilised to provide furtherfunctional groups, for example by reaction with an aminosilane, wherebythe amino groups add to the double bonds via a Michael additionreaction, so as to introduce alkoxy silane functionality of thepolyester oligomer(s). Any residual unsaturation may also be utilisedfor reaction with any fatty acid unsaturation.

[0081] Suitable monomers providing an acid component and an unsaturatedgroup include but are not limited to fumaric acid, maleic acid, maleicanhydride and hydroxyalkyl(meth)acrylates, for examplehydroxyethylmethacrylate.

[0082] The esterification polymerisation processes for making thepolyester oligomer(s) for use in the invention composition are wellknown in the art and need not be described here in detail. Suffice tosay that they are normally carried out in the melt using catalysts suchas tin-based catalysts and with the provision for removing any water (oralcohol) formed from the condensation reaction.

[0083] An organic solvent may optionally be added before or after thepolymerisation process to control the viscosity. Examples of solventsinclude water-miscible solvents such as N-methylpyrrolidone, glycolethers such as butyldiglycol, diglyme and alkyl ethers of glycolacetates or mixtures of N-methylpyrrolidone and methyl ethyl ketone.Optionally no organic solvents are added.

[0084] The polyester oligomer(s) may be dispersed in water usingtechniques well known in the art. An aqueous dispersion of the polyesteroligomer(s) may be readily prepared by adding water directly to the hotpolyester oligomer(s) melt until the desired solids content/viscosity isreached. Alternatively the polyester oligomer(s) may be dispersed inwater by adding an aqueous pre-dispersion (or organic solvent solution)of the polyester oligomer(s)to the water phase. Still further an aqueousdispersion may be prepared by dispersion of the solidified melt from thecondensation polymerisation directly into water. The solidified melt ispreferably in a form such as flake (which can often be obtained directlyfrom the melt) or comminuted solid (obtained for example by grinding).

[0085] The polyester oligomer(s) normally do not require the use of anexternal surfactant when being dispersed into water, althoughsurfactants and or high shear can be utilised in order to assist in thedispersion of the polyester oligomer(s) in water (even if it isself-dispersible). Suitable surfactants include but are not limited toconventional anionic, cationic and/or non-ionic surfactants such as Na,K and NH₄ salts of dialkylsulphosuccinates, Na, K and NH₄ salts ofsulphated oils, Na, K and NH₄ salts of alkyl sulphonic acids, Na, K andNH₄ alkyl sulphates, alkali metal salts of sulphonic acids; fattyalcohols, ethoxylated fatty acids and/or fatty amides, and Na, K and NH₄salts of fatty acids such as Na stearate and Na oleate. Other anionicsurfactants include alkyl or (alk)aryl groups linked to sulphonic acidgroups, sulphuric acid half ester groups (linked in turn to polyglycolether groups), phosphonic acid groups, phosphoric acid analogues andphosphates or carboxylic acid groups. Cationic surfactants include alkylor (alk)aryl groups linked to quaternary ammonium salt groups. Non-ionicsurfactants include polyglycol ether compounds and polyethylene oxidecompounds. The amount used is preferably 0 to 15% by weight, morepreferably 0 to 8% by weight, still more preferably 0 to 5% by weight,especially 0.1 to 3% by weight and most especially 0.3 to 2% by weightbased on the weight of the crosslinkable polyester oligomer(s).

[0086] The aqueous dispersion of the polyester oligomer(s) may be forexample, a colloidal dispersion of the polyester oligomer(s) in water(i.e. an emulsion or latex) or a solution (molecular dispersion) of thepolyester oligomer(s) in water, or a combination thereof.

[0087] The glass transition temperature (Tg) of the polyesteroligomer(s) may vary within a wide range. The Tg (as measured bymodulated differential scanning calorimetry) is preferably in the rangeof from −90 to 100° C., more preferably −90 to 50° C. especially −75 to30° C. and most preferably −60 to 10° C.

[0088] The aqueous composition of the invention may optionally butpreferably include a polymer dispersed therein which is not a polyesteroligomer (or a non-polyester oligomer whether crosslinkable ornon-crosslinkable) and has a Mw ≧120,000 Daltons, (herein termed adispersed polymer for convenience). Preferably the weight averagemolecular weight of the dispersed polymer(s) in the aqueous polymerdispersion is in the range of from 120,000 to 6,000,000, more preferablyin the range of from 150,000 to 2,000,000, and especially in the rangeof from 250,000 to 1,500,000. If the dispersed polymer(s) is fullypre-crosslinked its Mw will be infinite. Also, in some cases, thesynthesis to form the crosslinkable polyester oligomer(s) yields, inaddition to the polyester oligomer(s), an amount of very high molecularmaterial. For the purposes of this invention, such material, producedin-situ, is to be considered as a dispersed polymer. The Mw of thedispersed polymer(s) may be <120,000 Daltons with the proviso that thesolution viscosity of the dispersed polymer(s) is >150 Pa.s asdetermined from a 80% by weight solids solution of the dispersedpolymer(s) in at least one of the solvents selected from the groupconsisting of N-methyl pyrrolidone, n-butyl glycol and mixtures thereofusing a shear rate of 90±5 s⁻¹ and at 50±2° C.

[0089] Preferably the solution viscosity (if measurable) of thedispersed polymer(s) when used in the aqueous composition of theinvention is ≧250 Pa.s more preferably ≧500 Pa.s and especially ≧1000Pa.s, as determined from an 80% by weight solids solution of thedispersed polymer(s) in at least one of the solvents selected from thegroup consisting of N-methylpyrrolidone, n-butylglycol and mixturesthereof, using a shear rate of 90±5 s⁻¹ and at 50±2° C.

[0090] The solution viscosity of the dispersed polymer(s) may not bemeasurable if for example the weight average molecular weight is sohigh, so as to render the dispersed polymer(s) insoluble or if thedispersed polymer(s) is fully or partially crosslinked, again renderingthe dispersed polymer(s) insoluble.

[0091] The dispersed polymer(s) may be film forming or non-film formingat ambient temperature, preferably the dispersed polymer(s) is non-filmforming at ambient temperature (ambient temperature as used herein isdefined as 23±2° C). Preferably the aqueous composition of the inventiondoes include such a dispersed polymer(s).

[0092] The crosslinkable polyester oligomer(s) can thus be (andpreferably is) combined with a dispersed polymer(s) to further improvethe provision of a binder system for providing an aqueous compositionwith the desired balance of long open/wet edge time and reduced tackfree time.

[0093] The presence of the crosslinkable polyester oligomer(s) (asdiscussed above) provides the defined long open time and wet edge time,whilst the presence of the dispersed polymer(s) (e.g. a polymer latex)appears to assist in reducing the drying time of the composition, eventhough its presence may not be essential to achieve the definedrequirements in this respect.

[0094] Accordingly in a further, and preferred, embodiment of thepresent invention there is provided an aqueous coating composition asdefined herein additionally comprising a dispersed polymer(s). Thedispersed polymer(s) may for example be the product of an aqueousemulsion polymerisation or a preformed polymer dispersed in water.

[0095] Preferably the dispersed polymer(s) has a Tg measured using DSC,which is in the range of from −50 to 300° C., more preferably in therange of from 25 to 200° C. and most preferably in the range of from 35to 125° C. If the dispersed polymer(s) is a vinyl polymer, the vinylpolymer may be a sequential polymer, i.e. the vinyl polymer will havemore than one Tg. Especially preferred is a vinyl polymer with 10 to 50wt. % of a soft part with a Tg in the range of from −30 to 20° C. and 50to 90 wt. % of a hard part of with a Tg in the range of from 60 to 110°C. This combination provides an additional advantage of improved blockresistance of the resultant coating, especially when co-solvent levelsof 0 to 15 wt. %, more preferably 0 to 5 wt. % and most preferably 0 to3 wt. %. of the aqueous composition are used. A simple blend ofdispersed polymers with high and low Tg's may also be used to achievethe same or similar advantage. Blocking is the well-known phenomenon ofcoated substrates which are in contact tending to unacceptably adhere toeach other, particularly when under pressure, as for example in doorsand windows in their respective frames or when stacked.

[0096] Preferably the dispersed polymer(s) has an average particle sizein the range of from 25 to 1000 nm, more preferably 60 to 700 nm, mostpreferably 100 to 600 nm and especially in the range of from 175 to 500nm. The dispersed polymer may also have a polymodal particle sizedistribution.

[0097] The dispersed polymer(s) preferably has a low solubility in theaqueous medium of the composition of the invention, however some of thedispersed polymer(s) may be soluble measurable by the centrifuge test asdescribed herein. Preferably at least 30%, more preferably at least 60%,most preferably at least 90% and especially at least 94% by weight ofthe dispersed polymer(s) is present as insoluble polymer over the wholepH range.

[0098] The dispersed polymer(s) may for example be vinyl polymer,polyester, polyamide, polyepoxide, or a mixture thereof. The dispersedpolymer(s) may also be a hybrid of two or more different polymer typessuch as urethane-acrylic polymers (as described in for example U.S. Pat.No.5,137,961), epoxy-acrylic polymers and polyester-acrylic polymers.The dispersed polymer(s) may also be an organic-inorganic hybrid, forexample silica particles grafted with a vinyl polymer(s). Preferably thedispersed polymer(s) is a vinyl polymer. Blends of dispersed polymersmay of course also be used.

[0099] The dispersed polymer(s) may optionally contain carboxylic acidgroups. The dispersed polymer(s) preferably has an acid value below 150mgKOH/g, more preferably an acid value in the range from 3 to 120mg/KOH/g, most preferably an acid value in the range from 4 to 180 mgKOH/g, especially an acid value in the range from 5 to 30 mg KOH/g andmost especially an acid value in the range from 6 to 19 mgKOH/g. Thepreferred acid value of the dispersed polymer(s) depend on the nature ofthe crosslinkable polyester oligomer(s) and the amount of co-solvent inthe aqueous composition of the invention. If the oligomer ishydrophilic, the co-solvent if used is preferably also of a hydrophilicnature and a low acid value of the dispersed polymer(s) is preferred(preferably below 60, more preferably below 40, most preferably below24, and especially below 15 mg KOH/g). If however a hydrophobic oligomeris used, for instance based on (at least partly) unsaturated fatty acidand without dispersing groups, the cosolvent is preferentially of ahydrophobic nature (if at all present) and therefore much higher acidvalues (up to an acid value of 160, more preferred up to 125, mostpreferred up to 100 mg KOH/g) of the dispersed polymer(s) may betolerated to give the desired properties.

[0100] In a special embodiment, ≦15 wt. % of a co-solvent (based ontotal binder solids where the binder includes the oligomer(s) and anydispersed polymer(s)) is used, where the dispersed polymer(s) has anacid value below 20 mg KOH/g and the crosslinkable polyester oligomer(s)is present in an amount (based on total binder polymer solids) of 35 to65 wt. %, the crosslinkable polyester oligomer comprising 45 to 70 wt. %of fatty acid groups.

[0101] The dispersed polymer(s) may optionally contain hydroxyl groups.If the dispersed polymer(s) is a vinyl polymer comprising polymerised(meth)acrylic monomers then preferably the hydroxyl group content in thevinyl polymer is preferably below 1.0 wt. %, more preferably below 0.5wt. % and most preferably below 0.2 wt. % based on the weight of thevinyl polymer.

[0102] The dispersed polymer(s) may optionally contain amide groups(such as groups being for example obtainable from amide functionalmonomers such as (meth)acrylamide).

[0103] If the dispersed polymer(s) is a vinyl polymer comprisingpolymerised (meth)acrylamide monomers, then preferably the amide groupcontent in the vinyl polymer is below 3.0 wt. %, more preferably below1.5 wt. % and most preferably below 0.6 wt. % based on the weight of thevinyl polymer.

[0104] The dispersed polymer(s) may optionally contain wet-adhesionpromoting groups such as acetoacetoxy groups; (optionally substituted)amine or urea groups, for example cyclic ureido groups, imidazolegroups, pyridine groups, hydrazide or semicarbazide groups.

[0105] The dispersed polymer(s) may optionally contain crosslinkergroups which allow crosslinking of the dispersed polymer(s) and/or allowparticipation in the crosslinking reaction of the crosslinkablepolyester oligomer(s), thus speeding up the drying rate and improvingthe properties of the final coating (e.g. chemical resistance andscratch resistance). Examples of such crosslinker groups include groupswhich can take part in the autoxidation and groups which will effectcrosslinking other than by autoxidation, for example, Schiff base andsilane condensation reactions as discussed above for polyesteroligomer(s).

[0106] In a preferred embodiment the dispersed polymer(s) containscrosslinker groups which can participate in the preferred autoxidativecrosslinking reactions of an autoxidisably crosslinkable polyesteroligomer(s).

[0107] In a preferred embodiment the dispersed polymer(s) may bepartially or fully pre-crosslinked. If the dispersed polymer(s) is avinyl polymer pre-crosslinking may be achieved by using polyunsaturatedmonomers during the vinyl polymer synthesis such as allyl methacrylate,diallyl phthalate, tripropylene glycol di(meth)acrylate, 1,4-butanedioldiacrylate and trimethylol propane triacrylate (TMPTA). Allylmethacrylate is most preferred. Alternatively very low levels ofinitiator may be used, leading to chain-transfer to the vinyl polymerand hence to grafting and high Mw. Other ways to generatepre-crosslinking in a vinyl polymer is to include the use of monomer(s)bearing groups which may react with each other during synthesis toeffect pre-crosslinking for example glycidylmethacrylate and acrylicacid.

[0108] Vinyl polymer(s) are derived from free radically polymerisableolefinically unsaturated monomers (vinyl monomers) and can containpolymerised units of a wide range of such vinyl monomers, especiallythose commonly used to make binders for the coatings industry.

[0109] Examples of vinyl monomers which may be used to form vinylpolymer(s) include but are not limited to 1,3-butadiene, isoprene,styrene, ic-methyl styrene, divinyl benzene, acrylonitrile,methacrylonitrile, vinyl halides such as vinyl chloride, vinylidenehalides such as vinylidene chloride, vinyl esters such as vinyl acetate,vinyl propionate, vinyl laurate, and vinyl esters of versatic acid suchas VeoVa 9 and VeoVa 10 (VeoVa is a trademark of Shell), heterocyclicvinyl compounds, alkyl esters of mono-olefinically unsaturateddicarboxylic acids (such as di-n-butyl maleate and di-n-butyl fumarate)and, in particular, esters of acrylic acid and methacrylic acid offormula

CH₂═CR¹—COOR²

[0110] wherein R¹ is H or methyl and R² is optionally substituted alkylor cycloalkyl of 1 to 20 carbon atoms (more preferably 1 to 8 carbonatoms) examples of which are methyl acrylate, methyl methacrylate, ethylacrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate,2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isopropyl acrylate,isopropyl methacrylate, n-propyl acrylate, n-propyl methacrylate, andhydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate, hydroxyethylmethacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate,4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate and their modifiedanalogues like Tone M-100 (Tone is a trademark of Union CarbideCorporation).

[0111] Olefinically unsaturated monocarboxylic, sulphonic and/ordicarboxylic acids, such as acrylic acid, methacrylic acid, P-carboxyethyl acrylate, fumaric acid, itaconic acid, sodio-4-sulpho-styrene(SSS), acrylamidopropane sulphonic acid (AMPS), (meth)acrylamide,methoxypolyethyleneoxide (meth)acrylate may also be used.

[0112] The vinyl monomer may optionally contain functional groups tocontribute to the crosslinking of the vinyl polymer(s) in the coating.Examples of such groups include maleic, epoxy, fumaric, acetoacetoxy,p-diketone, unsaturated fatty acid, acryloyl, methacryloyl, styrenic,(meth)allyl groups, mercapto groups, keto or aldehyde groups (such asmethylvinylketone, diacetoneacrylamide and (meth)acrolein).

[0113] Particularly preferred are vinyl polymer(s) made from a monomersystem comprising at least 40 weight % of one or more monomers of theformula CH₂═CR¹COOR² defined above. Such preferred vinyl polymer(s) aredefined herein as acrylic polymer(s). More preferably, the monomersystem contains at least 50 weight % of such monomers, and particularlyat least 60 weight %. The other monomers in such acrylic polymer(s) (ifused) may include one or more of the other vinyl monomers mentionedabove, and/or may include ones different to such other monomers.Particularly preferred monomers include butyl acrylate, butylmethacrylate, methyl methacrylate, ethyl hexyl methacrylate, esters of(meth)acrylic acid, vinyl and vinylidene chloride, butadiene,acrylonitrile, vinyl acetate and styrene.

[0114] If the dispersed polymer(s) is a dispersed vinyl polymer, thedispersed vinyl polymer optionally comprises at least 15 wt. %, morepreferably at least 40 wt. % and most preferably at least 60 wt. % ofpolymerised vinyl acetate. If the dispersed vinyl polymer comprises atleast 50 wt. % of polymerised vinylacetate then preferably the dispersedvinyl polymer also comprises 10 to 49 wt. % of either butylacrylate or abranched vinylester, for example Veova 10.

[0115] In a preferred embodiment the dispersed vinyl polymer comprises:

[0116] I. 15 to 60 wt. % of styrene and/or (x-methylstyrene;

[0117] II. 15 to 80 wt. % of one or more of methyl methacrylate, ethylmethacrylate, cyclohexyl (meth)acrylate and n-butyl methacrylate;

[0118] III. 0 to 5 wt. % of vinyl monomer containing carboxylic acidgroups;

[0119] IV. 0 to 10 wt. %, more preferably 0 to 5 wt. % of a vinylmonomer containing non-ionic water-dispersing groups;

[0120] V. 5 to 40 wt. % of vinyl monomers other than as in I to IV, VIand VII;

[0121] VI. 0 to 5 wt. % of vinyl monomers containing wet adhesionpromoters or crosslinker groups (excluding any within the scope of IIIand VII); and

[0122] VII. 0 to 8 wt. %, more preferably 0 to 4 wt. %, and mostpreferably 0.5 to 3 wt. % of a polyethylenically unsaturated vinylmonomer,

[0123] wherein I)+II) add up to at least 50 wt. % andI+II+III+IV+V+VI+VII add up to 100%.

[0124] The dispersed polymer(s) can be prepared by any known technique.Preparation techniques include either dispersing a pre-formed polymer orpolymer solution in water or if the dispersed polymer(s) is a vinylpolymer directly synthesising the vinyl polymer in water (for example byemulsion polymerisation, micro-suspension polymerisation or miniemulsion polymerisation). Methods for preparing aqueous dispersedpolymer(s) are reviewed in the Journal of Coating Technology, volume 66,number 839, pages 89-105 (1995) and these methods are included herein byreference. Preferably dispersed vinyl polymer(s) are prepared by theemulsion polymerisation of free radically polymerisable olefinicallyunsaturated monomers (Emulsion Polymerisation and Emulsion Polymers, P.Lovell, M. S. El-Aasser, John Wiley, 1997). Any published variant of theemulsion polymerisation process may be utilised to prepare the dispersedpolymer(s), including the use of seeded emulsion polymerisationtechniques to control particle size and particle size distribution,especially when working in the particle size range 300-700 nm when theseeded technique is useful for giving good particle size control. Otheruseful techniques are the so called sequential polymerisation techniqueand the power feed technique (chapter 23 in “Emulsion Polymers andEmulsion Polymerisation” D R Basset and A E Hamielec, ACS SymposiumSeries No 165,1981).

[0125] Preferably the dispersed polymer(s) is colloid stable and it isalso desirable that colloid stability is maintained for as long aspossible into the drying process since early loss of colloid stabilitycan bring a premature end to open time. Since the final coatingcomposition may often contain co-solvents and dissolved ionic species(e.g. from pigment dissolution and from the presence of neutralisingagents), it is desirable that the colloid stability of the dispersedpolymer(s) is adequate to withstand any destabilising influences ofthese components. Colloid stability may be achieved by the addition ofconventional non-ionic surfactants, optionally with the addition ofanionic surfactants at any stage during the preparation of the aqueouscomposition of the invention. Strongly adsorbing surfactants capable ofproviding steric stability are preferred. Higher levels of colloidstability may be obtained by chemically binding or partially bindinghydrophilic stabilising groups such as polyethylene oxide groups to thesurface of dispersed polymer(s) particles. Suitable surfactants andstabilising groups are described in “Non Ionic Surfactants-PhysicalChemistry” (see for example M J Schick, M Dekker Inc 1987) and “PolymerColloids” (Buscall, Corner & Stageman, Elsevier Applied SciencePublishers 1985).

[0126] Chemical binding (grafting) of hydrophilic stabilising groupsonto dispersed polymer(s) particles can be achieved by the use of acomonomer, polymerisation initiator and/or chain transfer agent bearingthe stabilising group, for example methoxy(polyethylene oxide)₃₀methacrylate may be introduced as a comonomer into an emulsionpolymerisation to give rise to stabilised dispersed polymer particleswith bound polyethylene oxide groups on the particle surface. Anothermethod of producing a strongly sterically stabilised dispersedpolymer(s) is to introduce cellulosic derivatives (e.g. hydroxy ethylcellulose) during an emulsion polymerisation (see for example D H Craig,Journal of Coatings Technology 61, no.779, 48, 1989). Hydrophilicstabilising groups may also be introduced into a preformed polymerbefore it is subsequently dispersed in water, as described in EP 0317258where polyethylene oxide groups are reacted into a polyester polymerwhich is subsequently dispersed in water and then chain extended.

[0127] The combination of crosslinkable polyester oligomer(s) (and othercrosslinkable or non-crosslinkable oligomers if used) and dispersedpolymer(s) is most conveniently prepared by physically blending thecorresponding aqueous dispersions. However other methods of preparingthe combination can sometimes be utilised. One such method is to preparethe crosslinkable polyester oligomer(s) in solution as previouslydiscussed, and to disperse this solution directly into a dispersedpolymer(s). Alternatively the solvent can be removed from thecrosslinkable polyester oligomer(s) solution, and the polyesteroligomer(s) is directly dispersed into a dispersed polymer(s). Anothermethod is to introduce the crosslinkable polyester oligomer(s) into anaqueous free radical polymerisation reaction which produces thedispersed polymer(s). Such an introduction of polyester oligomer(s) caneither be at the commencement of the aqueous free radical polymerisationor during an aqueous free radical polymerisation. (Also as mentionedpreviously, a dispersed polymer can sometimes be formed in-situ from thesynthesis of a polyester oligomer(s) as a very high molecular weightpolymer fraction resulting from the polyester synthesis).

[0128] The crosslinkable polyester oligomer(s) may also be diluted withreactive diluent (for example vinyl monomers) at any stage of itspreparation and then dispersed into a dispersed polymer(s), followed bypolymerisation of the reactive diluent in the presence of the polyesteroligomer(s) and the optional polymer dispersion(s). Optionally,depending on the nature of the reactive diluent, no furtherpolymerisation of the reactive diluent prior to use in a coating may berequired.

[0129] Alternatively the crosslinkable polyester oligomer(s) anddispersed polymer(s) may be combined by preparing a redispersible drypowder form of the dispersed polymer(s), and then dispersing theredispersible dry powder directly into an aqueous dispersion of thecrosslinkable polyester oligomer(s). Methods for preparing redispersibledry powders from polymer emulsions are described for example in U.S.Pat. No.5,962,554, DE 3323804 and EP 0398576.

[0130] In an embodiment of the invention the crosslinkable polyesteroligomer(s) and the optional dispersed polymer(s) are compatible in thedrying aqueous composition. Preferably the crosslinkable polyesteroligomer(s) and the dispersed polymer(s) give clear films upon filmformation after coating of the aqueous composition onto a substrate.

[0131] Preferably the ratios by weight of solid material ofcrosslinkable polyester oligomer(s) (and other crosslinkable ornon-crosslinkable oligomers if used) to the dispersed polymer(s) in therange of from 100:0 to 10:90, more preferably in the range of from 90:10to 20:80, still more preferably in the range of from 80:20 to 25:75 andespecially in the range of 60:40 to 30:70.

[0132] The aqueous coating composition of the invention is particularlyuseful as or for providing the principle component of coatingformulations (i.e. composition intended for application to a substratewithout any further treatment or additions thereto) such as protectiveor decorative coating compositions (for example paint, lacquer orvarnish) wherein an initially prepared composition may be optionallyfurther diluted with water and/or organic solvents and/or combined withfurther ingredients, or may be in more concentrated form by optionalevaporation of water and/or organic components of the liquid medium ofan initially prepared composition. The invention composition can containco-solvent or a mixture of co-solvents. Preferably the inventioncomposition contains ±18% by weight of cosolvent(s), more preferably±10%, still more preferably ±5%, especially ±3% and most especially 0%by weight based on the invention composition. Preferably the evaporationrate of the co-solvent is ≦0.6, more preferably ≦0.15 most preferably≦0.08, and especially ≦0.035. Values for evaporation rates werepublished by Texaco Chemical Company in a bulletin Solvent Data: SolventProperties 1990. These values are relative to the evaporation rate ofn-butylacetate for which the evaporation rate is defined as 1.00.Determinaton of the evaporation rate of solvents that are not listed inthis bulletin is as described in ASTM D3539.

[0133] In a special embodiment, the amount of co-solvent used in theinvention composition is preferably linked to the Mw in the range 1,000to 120,000 Daltons, the amount of co-solvent is preferably 0 to 15 wt. %based on the weight of the composition, more preferably 0 to 10 wt. %.For oligomers with Mw in the range >50,000 to 100,000 Daltons, thecorresponding figures for the preferred amount of co-solvent are 0 to 25wt. %, more preferably 5 to 20 wt. %.

[0134] Furthermore, there is also a preferred relationship between theamount of co-solvent used and the amount of binder polymer solids, andthe amount of co-solvent is preferably ≦50 wt. % based on the weight ofbinder polymer solids in the composition, more preferably ≦35 wt. %,still more preferably ≦20 wt. %, most preferably ≦10 wt. % andespecially 0 wt. %.

[0135] An advantage of the current invention is that co-solvent can, ifas is often required for environmental and safety reasons, be present ata very low concentrations because of the plasticising nature of thecrosslinkable polyester oligomer(s). Preferably the solvent to waterratio is below 1.0, more preferably below 0.5, most preferably below 0.3and especially below 0.15. The co-solvent(s) can all be added at thefinal formulation step. Alternatively some or all of the co-solvent inthe final formulation can be the co-solvent utilised in the preparationof the crosslinkable polyester oligomer. An important consideration whenchoosing a co-solvent is whether or not the co-solvent is compatiblewith the crosslinkable polyester oligomer(s) and/or the dispersedpolymer(s) and the effect of any co-solvent partitioning (and thepartitioning of the co-solvent in the (aqueous) polyester oligomer phaseversus the dispersed polymer particles is preferably >1/1, morepreferably >2/1 and most preferably >3/1). If the co-solvent is morecompatible with the polymer it will swell the polymer, thus increasingthe overall viscosity. Preferably any co-solvent present in the aqueouscomposition of the invention is more compatible with the polyesteroligomer(s) then with the dispersed polymer(s), so that the dispersedpolymer(s) undergoes little if any swelling by the co-solvent. Theco-solvent selection is often determined by experimentation and/or bythe use of a solubility parameter concept i.e. maximising the differencein the solubility parameter of the dispersed polymer(s) and solventleads to a minimisation of the co-solvent uptake by the dispersedpolymer(s). Solubility parameters of a range of solvents and a groupcontribution method for assessing the solubility parameters of polymersare given by E A Grulke in the “Polymer Handbook” (John Wiley pages519-559, 1989) and by D W Van Krevelen and P J Hoftyzer in “Propertiesof Polymers. Correlations With Chemical Structure” (Elsevier, N.Y., 1972chapters 6 and 8). Co-solvent uptake of the dispersed polymer(s) may bedecreased by increasing the Tg so that the dispersed polymer(s) is inthe glassy region at ambient temperature, or by pre-crosslinking thedispersed polymer(s) as described above. Other ways of introducingpre-cross linking into dispersed polymer(s) are known in the art, forexample U.S. Pat. No.5,169,895 describes the preparation ofpre-crosslinked polyester aqueous dispersions by the use oftri-functional isocyanates in the synthesis.

[0136] A known problem with many autoxidisable coating compositions isthat the resultant coatings have a tendency to yellow, in particularwhere the autoxidisable groups are derived from polyunsaturated fattyacids, such as for example tung oil, linolenic acid, eleostearic acid,arachidonic acid, clupanadonic acid, and fatty acids obtainable fromdehydrated castor oil. This may be unacceptable depending on the desiredcolour of the resultant coating. Preferably the aqueous composition hasa starting yellowness value of less than 10, more preferably less than 7and most preferably less than 4, when measured using the test methoddescribed herein. Preferably the aqueous composition has an increase inyellowing in darkness of less than 7, more preferably less than 5, mostpreferably less than 3 and preferably the aqueous composition has anincrease in yellowing in daylight less than 12, more preferably lessthan 8 and most preferably less than 4 as measured by the test methoddescribed herein. Furthermore, the absolute yellowness (i.e. yellownessat start plus yellowness due to ageing) of the aqueous composition ispreferably less than 12, more preferably less than 10, still morepreferably less than 8, and most preferably less than 6.

[0137] In a further embodiment of the present invention there isprovides an aqueous coating composition as defined herein comprising:

[0138] i) 3 to 26% of a crosslinkable oligomer(s) by weight of thecomposition of which at least 52 wt % is said crosslinkable polyesteroligomer(s);

[0139] ii) 0 to 6.5% of a non-crosslinkable oligomer(s) by weight of thecomposition;

[0140] iii) 10 to 56% of dispersed polymer(s) by weight of thecomposition;

[0141] iv) 0 to 15% of co-solvent by weight of the composition;

[0142] v) 5 to 65% of water by weight of the composition;

[0143] where i)+ii)+iii)+iv)+v)=100%.

[0144] In another embodiment of the present invention there is providedan aqueous coating composition as defined herein comprising:

[0145] i) 15 to 40% of a crosslinkable oligomer(s) by weight ofcrosslinkable oligomer(s) and non-crosslinkable oligomer(s) anddispersed polymer(s) of which at least 52 wt % is said crosslinkablepolyester oligomer(s);

[0146] ii) 0 to 10% of a non-crosslinkable oligomer(s) by weight ofcrosslinkable oligomer(s) and non-crosslinkable oligomer(s) anddispersed polymer(s);

[0147] iii) 50 to 85% of dispersed polymer(s) by weight of crosslinkableoligomer(s) and non-crosslinkable oligomer(s) and dispersed polymer(s);

[0148] where i)+ii)+iii)=100%.

[0149] The aqueous coating composition of the invention may be appliedto a variety of substrates including wood, board, metals, stone,concrete, glass, cloth, leather, paper, plastics, foam and the like, byany conventional method including brushing, dipping, flow coating,spraying, and the like. They are, however, particularly useful forproviding coatings on wood and board substrates. The aqueous carriermedium is removed by natural drying or accelerated drying (by applyingheat) to form a coating.

[0150] Accordingly in a further embodiment of the invention there isprovided a coating obtainable from an aqueous coating composition of thepresent invention. The aqueous coating composition of the invention maycontain other conventional ingredients including pigments, dyes,emulsifiers, surfactants, plasticisers, thickeners, heat stabilisers,levelling agents, anti-cratering agents, fillers, sedimentationinhibitors, UV absorbers, antioxidants, dispersants, pigments,defoamers, co-solvents, wetting agents and the like introduced at anystage of the production process or subsequently. It is possible toinclude an amount of antimony oxide in the dispersions to enhance thefire retardant properties. Optionally external crosslinking agent(s) maybe added to the aqueous composition of the invention to aid crosslinkingduring or after drying. Examples of reactive functional groups which maybe utilised for external linking agent(s) include but are not limited tohydroxyl functional groups reacting with isocyanate (optionallyblocked), melamine, or glycouril functional groups; keto, aldehydeand/or acetoacetoxy carbonyl functional groups reacting with amine orhydrazine functional groups; carboxyl functional. groups reacting withaziridine, epoxy or carbodiimide functional groups; silane functionalgroups reacting with silane functional groups; epoxy functional groupsreacting with amine or mercaptane groups as well as carboxyl functionalgroups undergoing metal ion (such as zinc) crosslinking.

[0151] In particular, the aqueous coating compositions of the invention(if autoxidisable) and formulations containing them advantageouslyinclude a drier salt(s). Drier salts are well known to the art forfurther improving curing in unsaturated film-forming substances.Generally speaking, drier salts are metallic soaps, that is salts ofmetals and long chain carboxylic acids. It is thought that the metallicions effect the curing action in the film coating and the fatty acidcomponents confer compatibility in the coating medium. Examples of driermetals are cobalt, manganese, zirconium, lead, neodymium, lanthanum andcalcium. The level of drier salt(s) in the composition is typically thatto provide an amount of metal(s) within the range of from 0.01 to 0.5%by weight based on the weight of autoxidisable polyester oligomer(s) andor autoxidisable dispersed polymer(s).

[0152] Drier salts are conventionally supplied as solutions in whitespirit for use in solvent-borne alkyd systems. They may, however, beused quite satisfactorily in aqueous coating compositions since they cannormally be dispersed in such systems fairly easily. The drier salt(s)may be incorporated into the aqueous coating composition at anyconvenient stage. For example the drier salt(s) may be added prior todispersion into water. Drier accelerators may be added to the driersalts. Suitable drier accelerators include 2,2′-bipyridyl and1,10-phenanthroline.

[0153] If desired the aqueous dispersion of the invention can be used incombination with other polymer dispersions or solutions which are notaccording to the invention.

[0154] The present invention is now illustrated by reference to thefollowing examples. Unless otherwise specified, all parts, percentagesand ratios are on a weight basis. The prefix C before an example denotesthat it is comparative. The term “working” means that the example isaccording to the invention. The term “non-working” means that it is notaccording to the invention (i.e. comparative).

[0155] FIGS. 1 to 4 illustrate the drying profile of a compositionaccording to the present invention [Example 6], where the equilibriumviscosity is measured as the solids content increases.

[0156]FIG. 1 shows the drying profile measured using a shear rate of0.0997 s⁻¹.

[0157]FIG. 2 shows the drying profile measured using a shear rate of0.990 s⁻¹.

[0158]FIG. 3 shows the drying profile measured using a shear rate of9.97 s⁻¹.

[0159]FIG. 4 shows the drying profile measured using a shear rate of78.6 s⁻¹.

[0160] Test Methods:

[0161] To test the open time and wet edge time aqueous compositionsprepared as described in the examples below were applied using a wirerod to a test chart (18×24 cm, form 8B—display, available from LenetaCompany) at a wet film thickness of 120 μm. Open time and wet edge timetests were performed at fairly regular time intervals according to theapproximate expected final time in each case (being determined roughlyfrom a trial run), the intervals between measurements decreasing towardsthe end of the run. The measurements were carried out at relativehumidity levels of 50±5%, temperatures of 23±2° C. and an air flow ≦0.1m/s.

[0162] Open Time:

[0163] The open time was determined by brushing a virgin 75 cm² area ofthe coated chart with a brush (Monoblock no 12, pure bristles/polyester5408-12) carrying at regular intervals (as mentioned above) some more ofthe composition with a brush pressure of 100-150 g during 30 seconds. Inthis time the brush was moved in one set comprising 5 times in thedirection of the width of the substrate and 5 times in the direction oflength of the substrate before the coating was visually assessed. Oncethe composition carried on the brush no longer formed a homogeneouslayer with the coating on the substrate the open time was considered tobe over.

[0164] Wet Edge Time:

[0165] The wet edge time was determined by brushing at regular intervals(as mentioned above) a virgin 25 cm² edge area of the coated chart witha brush (Monoblock no 12, pure bristles/polyester 5408-12) carrying somemore of the composition with a brush pressure of 100-150 g during 30seconds. In this time the brush was moved in one set comprising 5 timesin the direction of the width of the substrate and 5 times in thedirection of length of the substrate before the coating was visuallyassessed. Once the composition carried on the brush no longer formed ahomogeneous layer with the coating on the substrate and/or a visible lapline could be seen the wet edge time was considered to be over.

[0166] Drying Time:

[0167] To test the dust-free, tack-free and thumb-hard drying stages ofthe aqueous compositions prepared in the Examples as described below,the composition was applied to a glass plate at a wet film thickness of80 μm. Drying time tests were performed at regular time intervals atrelative humidity levels of 50±5%, temperatures of 23±2° C. and an airflow ≦0.1 m/s.

[0168] Dust-Free Time:

[0169] The dust-free time was determined by dropping a piece of cottonwool (about 1 cm³ i.e. 0.1 g) onto the drying film from a distance of 25cm. If the piece of cotton wool could be immediately blown from thesubstrate by a person without leaving any wool or marks in or on thefilm, the film was considered to be dust-free.

[0170] Tack-Free Time:

[0171] The tack-free time was determined by placing a piece of cottonwool (about 1 cm³, 0.1 g) on the drying film and placing a metal plate(with a diameter of 2 cm) and then a weight of 1 kg onto the piece ofcotton wool (for 10 seconds). If the piece of cotton wool could beremoved from the substrate by hand without leaving any wool or marks inor on the film, the film was considered to be tack-free.

[0172] Thumb-Hard Time:

[0173] The thumb-hard time was determined by placing the coated glassplate on a balance and a thumb was pressed on the substrate with apressure of 7 kg. The thumb was then rotated 900 under this pressure. Ifthe film was not damaged the coating was dried down to the substratelevel and considered to be thumb-hard.

[0174] Viscosity:

[0175] All viscosity measurements were performed on a Bohlin RheometerVOR or a TA Instruments AR1000N Rheometer, using the cup & spindle(C14), cone & plate (CP 5/30) and/or plate & plate (PP15) geometry,depending on the approximate viscosity of the sample to be measured.

[0176] Solution Viscosity

[0177] For the solution viscosity measurements (both at 50±2° C. and at23±2° C.), the cone & plate (CP 5/30) geometry was used and themeasurements were performed at a shear rate of 92.5 s⁻¹. If the oligomersolutions were too low in viscosity to remain in between the cone andthe plate, the Cup & Spindle C14 geometry was used and the viscositymeasurements were performed at a shear rate of 91.9 s⁻¹. For bothgeometries, the gap between the Cone and the Plate (or between the Cupand the Spindle) was set to 0.1 mm, prior to each measurement. Thesolution viscosities of the oligomers were measured using the solventsystems and the conditions as defined herein in the statements ofinvention:

[0178] 1. The 80% solids solution: The oligomer was diluted (ifnecessary) with the appropriate solvent to an 80% solids solution (inNMP, BG or a mixture of NMP and BG at any ratio) which was homogenisedby stirring the solution for 15 minutes at 50±2° C.

[0179] 2. The 70% solids solution: The oligomer was diluted with theappropriate solvent (or mixture of solvents) to result in a 70% solidssolution (either in NMP/water/DMEA or in BG/water/DMEA, or in (a mixtureof NMP and BG at any ratio)/water/DMEA; in both solvent mixtures thesolvents should be present in a weight ratio of 20/7/3, respectively)which was homogenised by stirring the solution for 15 minutes at 50° C.The resulting solution was subsequently cooled prior to the viscositymeasurement at 23±2° C.

[0180] 3. A sample of oligomer solution was placed in the appropriatemeasurement geometry (Cone & Plate CP 5/30 or Cup & Spindle C14geometry). The solution viscosity of the oligomer was measured at atemperature of 50±2° C. for the 80% solids oligomer solution, and atambient temperature for the 70% solids oligomer solution. Aheating/cooling unit in the measurement geometry was used to control thetemperatures.

[0181] Equilibrium Viscosity:

[0182] The equilibrium viscosity measurements were performed with theplate & plate geometry, with a 15 mm (P15) top-plate and a 30 mm (P30)bottom-plate. The gap between the two plates was set to 1.0 mm. Allcompositions were used at the solids level at which they were preparedand not diluted to lower solids levels.

[0183] Step 1: Three test charts were provided with coatings ofidentical film thickness. The coatings were applied with a 120 μm wirerod and the actual film thickness (and its uniformity) was checked witha wet film gauge, 20-370 μm, of Braive Instruments. The charts weredried under identical conditions in an environment where the airflow was<0.1 m/s.

[0184] Step 2: One test chart was used to determine the solids increasein time. The weight of the film was monitored in time, starting rightafter application of the film. After calculating the solids content atevery measurement, a solids-time curve could be constructed and a trendline was calculated for the solids of the film as a function of thedrying time.

[0185] Step 3: The other two test charts were used to determine theequilibrium viscosity in time: approximately every 5 minutes a samplewas scraped from one test chart (in random order) and the viscosity ofthis sample was measured at 23° C. at representative shear rates of0.0997 s⁻¹, 0.990 s³¹ ¹, 9.97 s⁻¹ and 78.6 s⁻¹. The measurements werecontinued for 90 minutes, unless reproducible sampling from the testcharts could not be performed properly within that period of time (dueto for example drying of the film to reach the dust free time).

[0186] Step 4: The final drying curve of the coatings as shown in FIGS.1 to 4 (in which the equilibrium viscosity is represented as a functionof the solids of the drying film) could be constructed from thesolids-time curve (Step 2) and the equilibrium viscosity data (Step 3).If the equilibrium viscosity at a shear rate of 9.97s³¹ ¹, is lower thanthe equilibrium viscosity at a shear rate of 0.99s³¹ ¹, which is turn islower than the equilibrium viscosity at a shear rate of 0.0997s⁻¹, thecomposition may be regarded as shear thinning. If this was the case theequilibrium viscosity at 78.6s⁻¹ was not always measured as it wouldinherently always be lower than the equilibrium viscosity at a shearrate of 9.97s⁻¹.

[0187] Measurement of Yellowing:

[0188] The yellowness of a fresh coating and the increased yellowing ofa coating exposed to daylight or darkness for a specified time periodwas determined using a Tristimulus Colorimeter consisting of adata-station, a micro-colour meter, a calibration plate with a definedx, y and z value and a printer. The equipment was calibrated to thedefined values of the calibration plate and then colour co-ordinates L,a and b, were measured. The colour co-ordinates define the brightnessand colour on a colour scale, where ‘a’ is a measure of redness (+a) orgreenness (−a) and ‘b’ is a measure of yellowness (+b) or blueness (−b),(the more yellow the coating, the higher the ‘b’ value).The co-ordinates‘a’ and ‘b’ approach zero for neutral colours (white, grays and blacks).The higher the values for ‘a’ and ‘b’ are, the more saturated a colouris. The lightness ‘L’ is measured on a scale from 0 (white) to 100(black).

[0189] The yellowing in daylight is defined as in the increase of theyellowness (Δb-day) of the coating during storage at 23±2° C. and indaylight for 28 days. The yellowing in the dark is defined as theincrease in the yellowness (Δb-dark) of the coating during storage at23±2° C., in the dark for 14 days.

[0190] Molecular Weight Determination:

[0191] Gel permeation chromatography (GCP) analyses for thedetermination of polymer molecular weights were performed on an AllianceWater 2690 GPC with two consecutive PL-gel columns (type Mixed-C,I/d=300/7.mm) using tetrahydrofuran (THF) as the eluent at 1 cm³/min andusing an Alliance Waters 2410 refractive index detector. A set ofpolystyrene standards (analysed according to DIN 55672) was used tocalibrate the GPC.

[0192] Samples corresponding to about 16 mg of solid material weredissolved in 8 cm³ of THF, and the mixtures were stirred until thesamples had dissolved. The samples were left undisturbed for at lest 24hours for complete “uncoiling” and subsequently were filted (GelmanAcrodisc 13 or 25 mm ø CR PTFE; 0.45 μm) and placed on the auto-samplingunit of the GPC.

[0193] All species with a molecular weight less than 1000 Daltons wereignored when calculating the Mw and PDi for the oligomers. When Daltonsare used in this application to give molecular weight data, it should beunderstood that this is not a true molecular weight, but a molecularweight measured against polystyrene standards as described above.

[0194] Water Solubility Determination by a Centrifuge Test:

[0195] A sample of for example a crosslinkable polyester oligomer wasdispersed in water and diluted with water/ammonia to 10% solids and thepH adjusted to the desired pH, within a range of from 2 to 10, and thedispersion was then centrifuged over 5 hours at 21000 rpm at 23±2° C. ona Sigma 3K30 centrifuge (21,000 rpm corresponds to a centrifugal forceof 40,000 g. The pH chosen should be the pH where the crosslinkablevinyl oligomer is expected to be most soluble, for example often a pH ofabout 9 is suitable for anionic stabilised dispersions and a pH of about2 is often suitable for cationic stabilised dispersions. Aftercentrifugation a sample of the supernatant liquid was taken andevaporated for 1 hour at 105° C. to determine the solids content of thesupernatant liquid. The water solubility percentage was calculated bydividing the amount of solids (in gram) of the supernatant by the totalamount of solids put in the centrifuge tube and multiplying this by 100.

[0196] Water Resistance

[0197] The aqueous compositions prepared in the examples below were castdown on Leneta test charts Form 2C with a film thickness of 120 μm. Thefilms were dried at room temperature for 4 hours and at 50° C. for 16hours. After they were cooled down to room temperature the films weretested for water resistance. A few drops of water were placed on thefilms and covered with a watch glass. The water was removed after 16hours at room temperature and the damage to the coating was assessedimmediately and after four hours recovery. 0 Means that the coat isdissolved, 5 means that the coating is not affected at all. Materials &Abbreviations used: DEA = N,N-diethylethanolamine Cardura E10 =Neodecanoic acid-2,3-epoxypropyl ester available from Shell MPEG750 =methoxypolyethylene glycol (Mn apprxoximately 750) DMPA =dimethylolpropionic acid NMP = N-methyl pyrrolidone TDI = toluenediisocyanate Dowanol DPM = dipropylene glycol monomethyl ether DAPRO5005= drier salt available from Profiltra 1,4-CHDM =1,4-cyclohexanedimethanol Voranol P-400 = polypropyleneglycol availablefrom DOW Chemical A1310 = NCO functional silane component available fromCK Witco Corporation DMBA = dibutylbutanoic acid TMPME =trimethylolpropanemonoallyl ether TMPDE = trimethylpropanediallyletherIPDI = isophorone diisocyanate TEA = triethylamine Combi LS = drier saltavailable from Servo Delden Boltorn H20 = Dendritic polymer availablefrom Perstorp Nouracid LE80 = linseed oil fatty acid available from AKZONobel Fastcat 2005 = tin(II)chloride available from Elf-Atochem MEK =methyl ethyl ketone Atlas 4809 = Alkyl phenol alkoxylate available fromATLAS Chemie Atpol E5720/20 = Fatty alcohol ethoxylate available fromUniqema AP = ammonium persulphate Aerosol OT-75 = Sodiumdioctylsulphosuccinate available from Cytec MMA = methylmethacrylaten-BA = n-butylacrylate AA = acrylic acid SLS = Sodium Lauryl SulphateAkyposal NAF = Sodium dodecylbenzenesulphonate available from KAOChemicals Natrosol 250LR = Hydroxy ethyl cellulose available fromHercules Akyporox OP-250V = Octyl phenol ethoxylate available from KAOChemicals Surfactant = Phosphate ester of nonyl phenol ethoxylateavailable from KAO Chemicals VeoVa 10 = Vinyl ester of versatic acidavailable from Shell Desmodur W = dicyclohexyl methane diisocyanateavailable from Bayer Priplast 3192 = Dimeric acid polyester polyolavailable from Uniqema BMA = n-butyl methacrylate t-BHPO = t-butylhydroperoxide Fe^(III).EDTA = ferric ethylene diamine tetracetic acidIAA = isoascorbic acid solution STY = Styrene 2-EHA =2-Ethylhexylacrylate Dynasilan MEMO =3-Methacryloxypropyltrimethoxysilane available from Degussa HEMA =Hydroxyethylmethacrylate TEGDMA = Triethyleneglycoldimethacrylate OMKT =n-octyl mercaptane TAPEH = tert-amylperoxy-2-ethyl hexanoate SilquestA.174NT = 3-methacryloxypropyl trimethoxysilane available from WitcoWater = demineralised water PW602 = Transparent red iron-oxide pigmentdispersion available from Johnson Matthey AMP-95 =2-amino-2-methyl-1-propanol (available from Integrated Chemicals bv, 95%in water) Dehydran 1293 = Defoamer additive available from Cognis; 10%in butyl glycol Surfynol 104 E = wetting agent available from AirProducts; 50% in ethylene glycol NeoCryl BT-24 = Acrylic emulsionpolymer available from NeoResins, Avecia bv

[0198] Preparation of a poly-alkoxylated Adduct MPEG750/SAN:

[0199] A 2-L 3-necked round bottom flask, equipped with stirrer, wasloaded with methoxypolyethylene glycol (Mn ca. 750; 1323.53 g) andsuccinic anhydride (176.47 g) in a nitrogen atmosphere. The reactionmixture was heated to 120° C, and was stirred at this temperature untilall the anhydride had reacted, as judged from the Infra Red spectrum ofthe reaction mixture (the anhydride groups typically show twoabsorptions at 1785 cm⁻¹ and 1865 cm⁻¹, which disappeared and werereplaced by a new ester carbonyl absorption at 1740 cm⁻¹). The clearliquid product was then cooled to 50° C and collected. The productsolidified when left undisturbed at ambient temperature.

[0200] Crosslinkable Polyester Oligomer E1:

[0201] Phase 1: A 2 litre, five-necked reactor flask fitted with astirrer, a thermometer and a condenser fitted with a Dean-Starkcondensate trap, was loaded with adipic acid (156.49 g), Prifac 8961(sunflower oil fatty acid, Trademark from Uniqema; 391.22 g),trimethylol propane (TMP; 78.24 g) and pentaerythritol (PE; 130.41 g) ina nitrogen atmosphere. The resulting slurry was heated to 210° C. undervigorous stirring and the reaction water was distilled off. After twohours of reaction time, a portion of Fastcat 2005 (stannous(II)chloride,Trademark from Elf-Atochem; 0.26 g) was added to the reaction mixture.After 6 hours reaction time the acid value had dropped to 6.5 mg KOH/gand the viscous mixture was cooled to 120° C. In the second phasesuccinic anhydride (78.24 g) was added to the reaction mixture in oneportion. The contents of the reactor were stirred at 120° C. until allthe anhydride had reacted, as judged from the Infra Red spectrum of thereaction mixture (the anhydride groups typically show two absorptions at1785 cm⁻¹ and 1865 cm⁻¹, which disappeared and were replaced by a newester carbonyl absorption at 1740 cm⁻¹). The resultant acid-functionalpolyester oligomer E1 was cooled to room temperature and collected. Theoligomer had an acid value of 54 mg KOH/g.

[0202] The polyester oligomer had a viscosity of 523 mPa.s, whenmeasured at a shear rate of 91.9 5s⁻¹, at 50° C. and at a solids contentof 80% by weight in BG, and a viscosity of 1,130 mPa.s, when measured ata shear rate of 91.9 s⁻¹, at 23° C. and at a solids content of 70% byweight in a solvent mixture of BG/H₂O/DMEA=20/713.

[0203] The crosslinkable polyester oligomers E2 to E8 were preparedaccording to similar procedures using the components shown in Table 1below, with the following changes:

[0204] Crosslinkable Polyester Oligomer E2:

[0205] 3-Isocyanato-propyl triethoxy silane (Silquest A-1310)post-modification, for the preparation of oligomer E2, was performed bymixing the OH-functional hyper-branched polyester and IPTS at roomtemperature, followed by addition of a catalytic amount of dibutyltindilaurate and subsequent heating of the reaction mixture to 50° C. Themixture was stirred at this temperature until all the isocyanate hadreacted, as judged from the Infra Red spectrum of the reaction mixture(the NCO groups typically show an absorption at 2275 cm⁻¹). NMP was usedas co-solvent in this reaction.

[0206] Crosslinkable Polyester Oligomer E3:

[0207] The polyester oligomer E3, with a combination of fatty acid andallyl functionality, was prepared by the reaction of an OH-functionalfatty acid polyester oligomer (the product of phase 1 and 2), with SAN(phase 3), followed by the reaction of the resulting carboxylic acidgroup bearing polyester with allyl glycidyl ether (AGE) at 110° C.(phase 4).

[0208] Crosslinkable Polyester Amide Oligomer E8:

[0209] The polyester amide oligomer E8 was prepared from a fatty amide.The fatty amide was prepared by the reaction of N,N-diethanolamine withsunflower oil, catalysed by NaOMe, by stirring the reaction mixture for4 hours at 110° C. in a nitrogen atmosphere. The esterification reactionto form oligomer 8 was conducted at 180° C. until an acid value of 20 mgKOH/g was obtained. This acid value corresponds to the theoretical acidvalue when the acid group of DMPA is left unreacted. The OH value was264 mg/KOH.

[0210] Water Solubility

[0211] Crosslinking polyester oligomers E2, E4 and E7 were respectively100%, 7.9% and 32.5% water soluble as measured by the centrifuge test.TABLE 1 Components E2^(b) E3^(c) E4^(d) E5 E6 E7 E8 Isophthalic acid (g)— — — 93.86 — — — Adipic acid (g) 242.32 101.25 234.89 — — 300.00 295.61CHDA (g) — — — — 158.30 — — DMPA (g) — — — — — — 68.26 Levulinic acid(g) 170.20 — — — — 150.00 — Fatty acid — — Prifac Dedico Prifac Prifac —8961 5981 8961 8961 Fatty acid (g) — — 392.70 40.91 1273.50 500.00 —Fatty amide (g) — — — — — — 918.50 SSIPA (g) — 38.56 — — — 76.50 — NPG(g) 52.40 69.43 44.00 17.45 — 128.25 — Trimethylolpropane (g) 230.9160.26 328.84 54.88 134.10 280.00 — Pentaerythritol (g) — — — 24.55134.10 — — MPEG 750 (g) — — — — — — 72.00 MPEG 750/SAN (g) 55.12 120.22— 35.55 — — — CHDM (g) — — — — — — 31.62 SnCl₂.H₂O (catalyst) (g) 0.300.50 0.50 0.07 1.00 0.50 0.50 Acid value (mg KOH/g) 5.80 4.20 5.20 1.600.86 8.40 19.60 CoatOSil CS1770 (g) — 143.10 — — — — — SAN (g) 35.50 —60.00 43.40 — — — DMAP (g) 0.70 — 0.10 0.20 — — — DBTDL (g) — 0.10 — — —— — Allyl glycidyl ether (g) — — 57.00 — — — — DMBA (g) — — 4.00 — — — —BG (g) — — — — — — — NMP (g) — 125.03 9.90 71.82 — — — Final Acid value(mg KOH/g) 33.94 3.01 5.47 91.54 0.86 8.40 19.60 Solution viscosity*2950 10100 131 135000 41 336 198 Solution viscosity** 3920 5540 34988300 356 551 457 Mw 39456 32370 3621 24542 59300 3599 7422 PDi 21.615.7 2.0 12.4 6.7 2.7 3.5

[0212] Preparation of Dispersion dE1 from Crosslinkable PolyesterOligomer E1:

[0213] A 500 cm³ three-necked reactor flask fitted with a stirrer and athermometer was charged with the polyester oligomer E1 solution (200.0g, 80% solids) prepared above and the content was heated to 65° C. undera nitrogen atmosphere. At this temperature, a drier salt (DAPRO5005,trademark from Profiltra, 2.4 g), dipropylene glycol methyl ether (20.54g), ATLAS G4809 (trademark from Uniqema, 70% aqueous solution, 8.0 g),N,N-dimethyl ethanolamine (DMEA, 17.13 g) and water (53.86 g) weresubsequently added to the stirred polyester oligomer solution while thetemperature was kept at 65° C. The resulting mixture (275.0 g) wasslowly added over a period of 30 minutes to hot water (333.93 g, 50° C.)in a 1-L reactor under a nitrogen atmosphere while the temperature ofthe stirred aqueous phase was kept at 45 to 50° C. The resultingdispersion was stirred for an additional 30 minutes at 45 to 50° C andsubsequently cooled to room temperature, filtered and collected. Theresultant translucent polyester dispersion dE1 had a solids content of26.3%.

[0214] The crosslinkable polyester oligomer dispersions dE2 to dE8 wereprepared according to similar procedures using the components listed inTable 2 below. Polyester oligomers that were dispersed with the use of amini-emulsion prepared from the Atlas G5000, dodecanol and water (dE4,dE5 and dE6) were dispersed under high shear (Dispermat, 7000 rpm). DE8was first prepared as a predispersion. DE2 included as additives NH₃(25% aq, 4.55 g) and ADH (2.7 g) and dE7 included ADH (1.11 g) as anadditive. TABLE 2 Components dE2 dE3 dE4 dE5 dE6 dE7 dE8 Oligomer (g)50.00 51.00 50.00 42.90 50.00 50.00 150.00 Dodecanol (g) — — 2.00 2.002.00 1.32 — NMP or DPM* (g) — — — 8.58 2.50* — 22.5/15.0* DAPRO 5005 (g)or — — 1.00 1.00 1.00 1.00** 2.25 Borchersdry VP0133** (g) ATLAS G5000 —— 2.00 2.00 2.00 1.32 — Neutralising agent type DMEA NH₃ DMEA DMEA DMEANH₃ DMEA Neutralising agent (g) 2.80 3.16 0.40 5.20 0.06 0.55 4.67 Water(g) 106.20 81.80 72.10 26.05 72.40 101.87 36.78 Dispersion solids (%)31.7 30.1 40.9 40.1 40.1 33.0 65.0 Dispersion pH 8.2 7.9 7.1 7.7 7.0 7.67.7

[0215] Preparation of a Crosslinkable Urethane Oligomer U1, and ItsDispersion DU1:

[0216] The first step of this preparation provides anisocyanate-reactive material bearing crosslinker groups for use in thesynthesis of the self-crosslinkable polyurethane oligomer, theisocyanate-reactive groups being hydroxyl and the crosslinker groupsbeing fatty acid groups. A 1-L 3-necked round bottom flask, equippedwith a stirrer and a thermometer, was loaded with N,N-diethanolamine(DEA) (100.00 g), NaOMe (0.52 g) and sunflower oil (505.10 g) in anitrogen atmosphere. The hazy reaction mixture was stirred at 110-120°C. until a clear mixture was obtained. Stirring at the given temperaturewas continued until a DEA-conversion of at least 90% was achieved, asdetermined by titration of residual amine functionality in the productwith 1 N aqueous HCl. A conversion of 94% was achieved. The product wasthen cooled to room temperature and stored under nitrogen.

[0217] In the second step, a 1-L 3-necked round bottom flask, equippedwith a stirrer and a thermometer, was loaded with dimethylolpropanoicacid (DMPA; 19.36 g), N-methyl pyrrolidone (NMP; 92.50 g),methoxypolyethylene glycol (MPEG750; 18.87 g), cyclohexane dimethanol(CHDM; 8.97 g), the alkyd polyol mixture described above (260.43 g) andtoluene diisocyanate (TDI; 99.89 g). The reactor was purged withnitrogen and the reaction mixture was slowly heated to 50° C. andstirred at this temperature for 1 hour in a nitrogen atmosphere. Themixture was then heated to 80° C. and kept at this temperature for 1hour. The resultant NCO-free alkyd urethane oligomer U1 was then cooledto 70° C. and diluted with dipropylene glycol monomethyl ether (51.38g), N,N-dimethylethanolamine (DMEA; 10.27 g), DAPRO 5005 (5.84 g) andwater (155.43 g). The mixture was homogenised at 55 to 60° C. andsubsequently fed into water (907.1 g; 50° C.) in a separate reactor in anitrogen atmosphere. The product dispersion was cooled to ambienttemperature, filtered and stored in a nitrogen atmosphere. Thedispersion DU1 has a solids content of 24.2% and a pH of 7.1.

[0218] The viscosity of an 80% solids solution in NMP (50° C, shear rate91.1 s⁻¹) is 6.61 Pa.s.

[0219] The viscosity of a 70% solids solution in NMP/H₂O/DMEA (20/7/3)(23° C, shear rate 91.9 s⁻¹) is 10.91 Pa.s.

[0220] GPC analysis of U1: Mw=4,917; Mn=2,535; PDi=1.94

[0221] Acid value of U1=19.1 mgKOH/g

[0222] Preparation of a Non-Crosslinkable Urethane Oliqomer U2, and itsDispersion DU2:

[0223] In a nitrogen atmosphere, a 1-L 3-necked round bottom flask,equipped with a stirrer and a thermometer, was loaded withdimethylolpropanoic acid (DMPA; 48.00 g), N-methyl pyrrolidone (NMP;240.00 g), methoxypolyethylene glycol (MPEG750; 19.20 g) andpolypropylene glycol (Voranol P400, trademark from Dow Europe; 618.64g). At 50° C., toluene diisocyanate (TDI; 274.16 g) was fed into thispolyol mixture while the contents of the reactor were stirred. After theTDI feed was complete, the reaction mixture was heated to 80° C. andstirred at this temperature for 1 hour. The resultant NCO-free urethaneoligomer U2 was then cooled to 70° C.

[0224] A portion of this urethane oligomer (949.80 g) was diluted withdipropylene glycol monomethyl ether (97.60 g) andN,N-dimethylethanolamine (DMEA; 25.51 g) at 60° C. and the resultingmixture was stirred for 15 min at this temperature. Then hot water wasadded (50° C.; 295.25 g) and the resulting predispersion was stirred foran additional 15 min at 55 to 60° C. A portion of 1100.00 g of thismixture was subsequently fed into water (91 9.97 g; 50° C.) in aseparate reactor over a period of 60 minutes in a nitrogen atmosphere.After complete addition, the final dispersion was stirred for anadditional 15 minutes at 45-50° C., then cooled to ambient temperature,filtered and stored under nitrogen. The dispersion DU2 has a solidscontent of 24.2%, and a pH or 7.7.

[0225] The viscosity of an 80% solids solution in NMP (50° C., shearrate 91.1s⁻¹) is 57 Pa.s.

[0226] The viscosity of a 70% solids solution in NMP/H₂O/DMEA (20/7/3)(23° C., shear rate 91.9 s⁻¹) is 36.7 Pa.s.

[0227] GPC analysis of U2: Mw=10,251; Mn=4,476; PDi=2.29

[0228] Acid value of U2=20.93 mg/KOHg.

[0229] Preparation of Dispersed Vinyl Polymer P1

[0230] A 2-L 3-necked round bottom glass reactor, equipped with stirrer,thermometer and vortex breakers was loaded with demineralised water(652.57 g), Atpol E5720/20 (4.99 g) and Borax.10H2O (3.57 g) in anitrogen atmosphere. The mixture was heated whilst stirring to 80° C.and then a solution of AP (2.31 g) in demineralised water (16.00 g) wasadded. In a dropping funnel a pre-emulsion was prepared by stirring amixture of demineralised water (161.87 g), Atpol E5720/20 (94.85 g),Aerosol OT-75 (7.20 g), Borax.10H2O (1.07 g), MMA (534.18 g), n-BA(444.32 g) and AA (19.97 g). 5% of this pre-emulsion was added to thereactor at 80° C. over 5 minutes. The remainder was fed into the reactorover 160 minutes at 85° C. A solution of AP (0.53 g) in demineralisedwater (7.88 g) was added to the reactor during the first 15 minutes offeeding the pre-emulsified feed. Then the reactor content was kept at85° C. for 30 minutes, and then cooled to ambient temperature. The pHwas adjusted to 8 to 8.5 with 12.5% aqueous ammonia. The resultantproduct (P1) was filtered and collected.

[0231] The properties of P1 are listed in Table 4.

[0232] Preparation of a Sequential Dispersed Vinyl Polymer P2

[0233] A 2-L 3-necked round bottom glass reactor, equipped with stirrer,thermometer and vortex beakers, was loaded with demineralised water(990.94 g), SLS (30%, 0.55 g) and NaHCO₃, (4.44 g) in a nitrogenatmosphere. The mixture was heated whilst stirring to 80° C. and then asolution of AP (0.89 g) in demineralised water (5.00 g) was added. In adropping funnel a monomer mixture was prepared by stirring MMA (140.48g), n-BA (207.71 g) and AA (7.1 1 g). 10% of this mixture was added tothe reactor at 80° C. The remainder was fed into the reactor over aperiod of 40 minutes at 85° C. The content of a separate droppingfunnel, containing demineralised water (20.00 g), AP (0.36 g) and SLS30% (11.62 g) was added in the same time. The reactor content was keptat 85° C. for 30 minutes. A second monomer mixture was prepared in adropping funnel consisting MMA (464.91 g), n-BA (57.37 g) and AA (10.66g). The mixture was fed to the reactor after the 30 minutes period in 60minutes. The content of a separate dropping funnel, containingdemineralised water (30.00 g), AP (0.53 g) and SLS 30% (17.44 g) wasadded in the same time. The reactor content was kept at 85° C. for 45minutes and then cooled to ambient temperature. The pH was adjusted to 8to 8.5 with 12.5% aqueous ammonia. The resultant product P2 was filteredand collected.

[0234] The properties of P2 are listed in Table 4.

[0235] Preparation of Dispersed Vinyl Polymer P3

[0236] A 2-L 3-necked round bottom glass reactor, equipped with stirrer,thermometer and vortex breakers, was loaded with demineralised water(194.50 g), Akyposal NAF (3.00 g), Borax.10H2O (1.25 g), Acetic acid(0.50 g) and Natrosol 250LR (10.00 g) in a nitrogen atmosphere. Themixture was heated whilst stirring to 60° C. and then a solution of AP(0.50 g) in demineralised water (10.00 g) was added. In a droppingfunnel a pre-emulsion was prepared by stirring with demineralised water(171.71 g), Akyposal NAF (3.00), Borax.10H2O (1.25 g), Acetic acid (0.50g) and Akyporox OP-250V (14.29 g) followed by VeoVa 10 (125.00 g) andvinyl acetate (375.00 g). 10% of this mixture was added to the reactorat 60° C. The mixture was heated whilst stirring to 80° C. The remainderwas fed into the reactor over 90 minutes at 80° C. The content of aseparate dropping funnel, containing a solution of AP (1.15 g) indemineralised water (60.00 g), was added in the same time. Then thereactor content was kept at this temperature for 120 minutes and thencooled to ambient temperature. The pH was adjusted to 8 to 8.5 with12.5% aqueous ammonia. The resultant product P3 was filtered andcollected.

[0237] The properties of P3 are listed in Table 4.

[0238] Preparation of the Dispersed Urethane Acrylic Polymer P4

[0239] Stage 1: A 1-L 3-necked round bottom flask, equipped with astirrer and a thermometer, was loaded with NMP (100.00 g), DMPA (24.00g), Desmodur W (152.68 g) and Priplast 3192 (223.33 g) in a nitrogenatmosphere. The reaction mixture was heated to 55° C., tin octoate(0.05) was added and the temperature was raised to 90-95° C. The mixturewas kept at this temperature for 1 hour before adding tinoctoate (0.05)and the mixture was kept at 90° C. for an additional hour. TheNCO-concentration of the mixture was found to be 4.83%. The resultingNCO terminated urethane prepolymer (500.05 g) (from which samples of atotal weight of 10.0 g were taken for % NCO determination, leaving490.05 g of prepolymer) was then cooled to 70° C, neutralised with TEA(17.75 g) diluted with BMA (196.02 g) and homogenised for 15 minutes at65° C.

[0240] Stage 2: A 2-L 3-necked round bottom flask, equipped with astirrer and thermometer, was loaded with a water phase consisting ofwater (1045.77 g) and BMA (174.00 g) in a nitrogen atmosphere. A portionof the urethane prepolymer (625.00 g) prepared in Stage 1 (at 60-65° C.)was fed into the reactor over 1 hour, keeping the temperature of thereactor contents below 30° C. After the feed was complete, the mixturewas stirred for an additional 5 minutes before chain-extension by theaddition of an aqueous 64.45% hydrazine hydrate solution (N₂H₄.H₂O,11.43 g in 25.00 g H₂O). A reactor temperature of 36° C. was reached.Subsequently, a 5% aqueous initiator solution of t-BHPO (18.10 g) and a1% aqueous solution of Fe^(III).EDTA; 4.63 g) was added to the reactionmixture. The radical polymerisation was started by the addition of a 1%aqueous iAA (45.24 g) and the reaction temperature was allowed to reach56° C. before more aqueous iAA (45.24 g) was added. The reaction mixturewas homogenised for 15 minutes, then cooled to room temperature,filtered over a 200-mesh sieve and collected. The properties of P4 arelisted in Table 4.

[0241] Preparation of Dispersed Vinyl Polymer P5

[0242] A 2-L 3-necked round bottom glass reactor, equipped with stirrer,thermometer and baffles, was loaded with demineralised water (990.94 g),SLS 30% (0.55 g) and NaHCO₃ (4.44 g) in a nitrogen atmosphere. Themixture was heated whilst stirring to 80° C. and then a solution of AP(0.89 g) in demineralised water (5.00 g) was added. STY (468.54 g),2-EHA (361.69 g) and M (58.00 g) were mixed in a dropping funnel. 10% ofthis mixture was added to the reactor at 80° C. and remainder was fedinto the reactor over 100 minutes at 85° C. The content of a separatedropping funnel, containing demineralised water (50.00 g), AP (0.89 g)and SLS 30% (29.06 g) was added in the same time and the reactor contentwas kept at 85° C. for 45 minutes and then cooled to 60° C. At 60° C. aburn-up was applied by adding a solution of iAA (2.60 g) indemineralised water (49.00 g) to the reactor followed by a mixture oft-BHPO (80%,2.40 g) and demineralised water (18.00 g). After 60 minutesthe reactor content was cooled to ambient temperature. The pH wasadjusted to 8 to 8.5 with 12.5% aqueous ammonia. The product P5 wasfiltered and collected. The properties of P5 are listed in Table 4.

[0243] Preparation of Dispersed Polymers P6 to P11 and P13 and P14

[0244] The dispersed polymers P6 to P11 and P13 and P14 were preparedusing the method described for P5 with the variations as listed in Table3. The properties of P6 to P11 are listed in Table 4. P13 has a weightaverage molecular weight of 22097, an Mn of 10451 and a PDi of 2.11. TheMn's and Mw's of P1 to P12 and P14 could not be measured.

[0245] Preparation of a Fatty Acid Functional Dispersed Polymer P12

[0246] In a 1L 3-necked round bottom reactor, equipped with stirrer andN₂ inlet, Nouracid LE80 (398.8 g), GMA (201.2 g), Irganox 1010 (0.10 g),Phenothiazine (0.10 g) and benzyl trimethylammonium hydroxide (40 wt %in water; 1.05 g) were loaded. The reactor was purged with nitrogen andthe yellow reaction mixture was heated and stirred at 155° C. until theacid value had dropped to 3.7 mg KOH/g. After cooling to ambienttemperature, the product was collected and stored under nitrogen.

[0247] A portion of 161.3 g of this adduct was mixed with MAA (40.3 g)and transferred into a dropping funnel. This mixture was slowly addedover a period of one hour to a 1L 3-necked round bottom reactorcontaining a solution of lauroyl peroxide (21.4 g) in butyl glycol(273.0 g) at 125° C. in a nitrogen atmosphere. After complete addition,the resulting copolymer solution was cooled to 50° C. and subsequentlyconcentrated in vacuo to 80% solids using a rotary evaporator. To theresulting yellow solution, a mixture of water (580.0 g), aqueous ammonia(25%; 12.0 g) and SLS (4.4 9) was added at 70° C. A mixture of MMA(225.5 g) and BA (92.5 g) was added to the resulting dispersion and thereaction mixture was stirred for 30 minutes at 70° C. The reactionmixture was heated to 85° C. and a solution of ammonium persulphate(0.86 g) in water (20.0 g) was added over a period of 10 min. Themixture was stirred at 85° C. for 3 h. Then a second portion of ammoniumpersulphate (0.86 g) in water (20.0 g) was added and the mixture wasstirred at 85° C. for 30 minutes. Then a third portion of ammoniumpersulphate (0.86 g) in water (20.0 g) was added and the mixture wasstirred for an additional 30 minutes at 85° C. The resulting dispersionwas cooled to ambient temperature, filtered and stored under nitrogen.The dispersion had a solids content of 39.3%, a pH of 7.7 and contained2.59% butyl glycol on total dispersion. TABLE 3 Components (g) P6 P7 P8P9 P10 P11 P13 P14 Reactor phase Water 912.19 960.66 990.94 1001.24960.66 990.94 1001.84 952.57 SLS 30% — 72.94 0.55 — 72.94 0.55 — —Surfactant 0.83 — — — — — — 0.92 NaHCO₃ 4.12 4.38 4.44 4.46 4.38 4.444.39 4.57 Shot at 80° C. AP 0.83 0.88 0.89 0.89 0.88 0.89 0.88 0.92water 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.52 Monomer mixture STY — — —— — 399.70 — — MMA 577.36 332.60 617.32 352.94 759.26 124.35 346.07611.55 BA 236.86 402.63 253.15 521.85 89.76 133.24 511.70 239.02 BMA — —— — — 204.29 — — AA 16.62 17.77 17.85 17.51 17.77 17.51 18.29 MAA —87.53 — — — — — — Dynasilan MEMO 41.54 — — — — — — — HEMA — 52.52 — — —— — — TEGDMA — — — — 8.75 — — — IOTG — — — — — — 17.01 — AAEM — — — — —— — 45.73 Separate feed water 50.00 50.00 50.00 50.00 50.00 50.00 50.0052.50 AP 0.83 0.88 0.89 0.89 0.88 0.89 0.88 0.92 SLS 30% — — 29.06 14.88— 29.06 14.59 — Surfactant 123.79 — — — — — — 136.72

[0248] TABLE 4 Parameter P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14Solids [wt %] 51.2 45.1 50.3 35.2 42.4 44.6 21.4 45.0 45.0 44.6 44.339.3 44.5 44.5 pH 8.3 8.3 8.2 7.9 8.3 8.2 8.0 8.2 8.2 8.3 8.2 7.7 8.48.4 Particle size [nm] 450 230 330 65 255 390 69 307 590 67 230 — 350406 Measured Tg*[° C.] 25 2 24 43 27 58 40 57 2 96 54 49 −7 51 Acidvalue** 15.6 15.6 0 12.4 50.6 15.6 63.4 15.6 15.6 15.6 15.6 — 15.6 15.6

[0249] Preparation of Blends of the Dispersed Oligomers and DispersedPolymers Prepared Above.

[0250] Preparation of a Blend of Oligomer Dispersion DE1 and DispersedPolymer P1=E1P1

[0251] In a nitrogen atmosphere, a 1-L 3-necked round bottom flask,equipped with a stirrer, was loaded with dispersion DE1 (75.00 g) andthe vinyl polymer latex P1 (38.50 g). The mixture was stirred for 30minutes at ambient temperature, filtered and then stored under nitrogen.The resultant dispersion E1P1 had a solids content of 34.71% by weight.

[0252] The oligomer/polymer blends listed in Table 5 below were preparedusing the method described above for E1P1. TABLE 5 Components DE1 E1P1E1P2 E1P3 E1P4 E2P5 Oligomer DE1 E1 E1 E1 E1 E2 Oligomer (g) 130.0075.00 75.00 75.00 75.00 100.00 Oligomer (% of solids) 100.00 50.00 50.0050.00 50.00 70.00 Polymer — P1 P2 P3 P4 P5 Polymer (g) — 38.50 43.7039.20 56.00 32.10 Polymer (% of solids) — 50.00 50.00 50.00 50.00 30.00Dispersion solids % 26.3 34.7 33.2 34.5 30.1 34.4 pH 8.5 8.5 8.4 8.5 8.47.4 Components E3P6 E4P7 E5P8 E6P9 E6P13 E8P8 Oligomer E3 E4 DE5 DE6 DE6DE8 Oligomer (g) 100.00 40.00 81.80 17.20 19.63 150.00 Oligomer 35.0030.00 80.00 15.00 15.00 40.00 (% of solids) Polymer P6 P7 P7 P8 P9 P8Polymer (g) 108.70 174.50 12.20 86.50 100.00 325.00 Polymer 65.00 70.0020.00 85.00 85.00 60.00 (% of solids) Additive — DPM — Water Water WaterAdditive (g) — 42.50 — 10.00 10.00 66.67 Dispersion 35.6 20.7 40.6 40.340.3 45.0 solids % pH 7.6 7.7 8.1 8.2 8.4 8.3 Components E2U1P10E1E3U2P11 E7P12 E7P14 Oligomer DE2/DU1 DE1/DE2/DU2 DE7 DE7 Oligomer (g)18.70/99.20 21.40/10.9/42.4 35.00 35.00 Oligomer 60.00 60.00 40.00 30.00(% of solids) Polymer P10 P11 P12 P14 Polymer (g) 44.80 31.80 68.5094.20 Polymer 40.00 40.00 60.00 70.00 (% of solids) Additive — —Borchersdry BG VP0133 Additive (g) — — 0.30 5.00 Dispersion 30.7 33.043.2 44.6 solids % pH 7.2 8.1 7.2 7.0

EXAMPLE 1

[0253] Pigmented Paint Composition Comprising Dispersion DE1:

[0254] A 1-L 3-necked round bottom flask, equipped with a stirrer, wasloaded with dispersion DE1 (130.00 g) and TiO₂-based pigment paste(C830; 42.10 g; solids content of 74.9%) in a nitrogen atmosphere, andthe mixture was stirred for 30 minutes at ambient temperature. Theresulting paint formulation had a solids content of 36.8%. Then thewetting agent (Byk 344; 0.1-0.2% on paint solids) and finally a urethanethickener (Borchigel L75N, Trademark from Bayer, approximately 1.5 g)was added until a suitable paint-viscosity was obtained (4,000 to 6,000mPa.s). The paint formulation was left is undisturbed for 24 h, thenstirred up to mix the contents intimately, checked (and when necessarycorrected) for its viscosity, and finally tested on drying and otherproperties.

[0255] C830 is a pigment formulation comprising TiO₂ (24.0 g), AMP-95(0.2 g), water (3.3 g), Dehydran 1293 (0.5 g), Surfinol 104 E (0.4 g).

[0256] Paint examples 2 to 14 and 16 (and the comparative examples C6,C8 and C10) were prepared according to similar procedures using thecomponents presented in Table 6. Example 17 demonstrates the use of theoligomer/polymer system used in working example 14 as a working clearcoat (i.e. non-pigmented) system. Example 15 uses an iron oxide pigmentinstead of C830. The drying and other properties of these examples arealso presented in Table 6.

[0257] The water resistance of example 14 and Example 16 before recoverywas 5 and after recovery was 5. The sandability of examples 7, 13 and 16were 2.5 hours, 22 hours and 18 hours respectively.

COMPARATIVE EXAMPLE 18

[0258] P5 was formulated with butyl glycol (8.48 g) and the resultingdispersion was thickened with Borchigel L75N to a viscosity of 4000 to6000 mPa.s.

COMPARATIVE EXAMPLE 19

[0259] P7 was used without further formulation. TABLE 6 Example 1 2 3 45 6 7 Binder DE1 E1P1 E1P2 E1P3 E1P4 E2P5 E3P6 Binder (g) 130.00 113.50118.70 114.20 131.00 132.10 208.70 Pigment C830 (g) 42.10 48.50 48.5048.50 48.50 55.90 91.80 Open Time (mins) 140 30 50 45 50 32 28 Wet edgetime (mins) 70 17 30 18 20 17 13 Dust-free time (mins) 135 30 40 35 3535 18 Tack-free time (h) 15 6 1.5 2 2.5 3.5 0.8 Thumb-hard time (h) 2424 6 9 6 6 2 Yellowness at start 3.69 3.49 2.78 3.02 2.6 2.21 1.62Yellowing (Δb-dark) 6.07 3.77 3.16 3.46 2.94 0.16 0.28 Yellowing(Δb-day) 2.69 0.86 0.85 1.02 1.37 0.29 0.33 Example 8 9 10 11 12 13Binder code E4P7 E5 E6 E2U1P10 E1E3U2P11 E7 Binder (g) 257.00 94.00113.70 162.70 106.60 103.80 Pigment C830 (g) 65.60 50.30 56.30 61.6043.40 55.30 Open Time (mins) 25 34 30 65 23 59 Wet edge time (mins) 1216 18 24 15 16 Dust-free time (mins) 45 140 25 30 30 30 Tack-free time(h) 2.5 18 2 3 3 1 Thumb-hard time (h) 3.5 24 6 4 6 2.5 Yellowness atstart 2.18 5.59 4.85 4.67 2.6 2.52 Yellowing (Δb-dark) 1.47 4.22 1.272.61 2.27 0.77 Yellowing (Δb-day) 0.33 0.93 −0.43 1.15 1.12 1.58 Example14 15 16 17 C18 C19 Binder code E7P14 E7P14 E8 E7P14 P5 P7 Binder (g)129.20 85.00 130.00 81.83 100 100 Pigment paste (g) C830 73.70 PW602,3.0 g 72.01 — — — Open Time (mins) 52 52 42 65 35 45 Wet edge time(mins) 17 16 14 27 7 8 Dust-free time (mins) 30 40 20 30 15 30 Tack-freetime (hours) 0.8 1.3 1.5 0.8 1.5 0.5 Thumb-hard time (hours) 1 1.5 1.5 72 1 Yellowness at start 2.74 — 3.39 — — — Yellowing (Δb-dark) 0.19 —3.15 — — — Yellowing (Δb-day) 0.89 — 1.80 — — —

[0260] Equilibrium Viscosity Data of the Examples Prepared Above

[0261] The equilibrium viscosity of the examples prepared above wasmeasured using a number of shear rates and the results are tabulatedbelow in Tables 7 to 25. TABLE 7 Example 1: Shear rate Shear rate Shearrate Shear rate 0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculatedviscosity viscosity viscosity viscosity (min) Solids (%) (Pa · s) (Pa ·s) (Pa · s) (Pa · s) 2.0 37.04 16 14 9 7 14.0 40.97 52 28 18 7 30.047.27 394 258 74 — 34.0 49.27 1770 456 259 — 40.0 52.32 1840 471 259 —43.5 54.24 821 168 52 — 50.0 57.7 883 178 54 — 57.0 61.9 1770 192 40 —63.5 64.93 1700 193 42 20 69.0 66.43 2080 226 47 21 76.5 67.76 1950 23149 22

[0262] TABLE 8 Example 2 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 7 49.8 113.0 30.2 12.2 4.6 11 51.9 171.0 43.3 15.9 5.8 1654.4 261.0 51.2 17.9 5.3 18 55.4 300.0 61.6 20.1 5.0 23 57.9 359.0 64.717.6 4.6 31 61.7 916.0 152.0 28.6 5.7 36 64.1 2640.0 389.0 60.7 — 3865.0 2480.0 358.0 47.7 — 43 67.2 5020.0 646.0 87.9 18.6 48 69.4 10200.02010.0 213.0 58.2 53 71.6 22800.0 4610.0 440.0 — 62 75.3 23700.0 4940.0691.0 126.0 69 78.0 33100.0 4770.0 424.0 —

[0263] TABLE 9 Example 3: Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity Viscosity (min) Solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 3.0 45.22 176 46 17 7 11.0 48.71 358 65 26 10 22.0 53.91 513103 52 15 28.5 57.22 427 159 70 — 35.0 60.69 1630 363 75 — 40.0 63.482460 515 — — 46.0 66.95 2390 492 105 — 52.0 70.57 11100 — — —

[0264] TABLE 10 Example 4: Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) Solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 1.0 45.01 126 23 11 4 7.0 47.50 113 25 13 5 13.0 50.14 23544 22 9 17.5 52.21 153 52 27 11 24.0 55.36 275 104 48 19 28.0 57.39 337134 56 — 34.0 60.57 1530 303 76 — 39.0 63.36 2520 482 117 — 46.0 67.4818200 3890 285 — 52.0 71.22 30800 8070 — — 57.0 74.50 28000 — — —

[0265] TABLE 11 Example 5: Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity Viscosity (min) Solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 0.0 41.06 187 50 17 8 7.0 43.17 275 54 21 9 13.0 45.22 42492 35 13 19.0 47.47 727 163 53 17 23.5 49.29 594 152 50 129 30.0 52.131920 543 122 — 34.5 54.25 3160 699 165 — 40.0 56.99 6840 1030 255 — 44.059.09 9840 1520 300 — 50.0 62.42 41100 — — —

[0266] TABLE 12 Example 6 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 7 50.5 33.7 14.3 8.0 6.3 18 57.0 43.8 23.6 13.5 8.6 23 60.174.9 31.7 17.8 8.5 28 63.2 130.0 55.1 28.3 13.2 33 66.4 293.0 97.6 47.017.1 39 70.4 871.0 186.0 84.9 48.0 44 73.8 1630.0 582.0 402.0 288.0 5279.3 3060.0 1140.0 626.0 250.0 58 83.6 66200.0 — — —

[0267] TABLE 13 Example 7 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 7 50.5 382.0 51.0 22.9 12.1 13 53.2 260.0 52.0 24.5 15.6 1855.6 1140.0 106.0 49.1 16.8 23 58.2 876.0 92.2 51.8 — 28 60.9 2760.0268.0 98.3 20.5 39 67.3 18300.0 3490.0 722.0 — 44 70.4 — — — — 46 71.613000.0 2190.0 443.0 — 51 74.9 — — — —

[0268] TABLE 14 Example 8 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 6 39.4 27 17 6 2 10 40.7 49 22 7 2 19 43.9 363 90 18 — 2245.1 854 136 27 — 31 48.6 243 46 18 33 36 50.8 580 97 108 73 42 53.43160 1140 521 94 51 57.6 2580 1790 592 108 57 60.6 3130 2770 900 323

[0269] TABLE 15 Example 9 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 3 52.5 22.5 15.2 9.4 7.8 7 54.0 34.9 20.9 13.2 10.8 15 56.867.3 35.7 21.4 17.1 18 57.8 184.0 62.4 24.1 16.6 25 59.9 115.0 47.1 25.218.3 29 61.0 114.0 44.7 26.6 19.5 35 62.5 298.0 78.5 34.4 22.2 41 63.9435.0 94.7 39.8 24.2 47 65.0 529.0 113.0 46.5 26.3 54 66.2 688.0 138.056.5 30.1 60 67.0 836.0 167.0 65.5 32.7 65 67.6 907.0 181.0 67.9 32.5 6867.9 948.0 189.0 74.0 33.8 73 68.3 1080.0 197.0 76.9 — 81 68.6 1130.0233.0 91.0 36.1 93 68.6 1540.0 322.0 133.0 — 98 68.4 1530.0 334.0 133.0— 103 68.1 1680.0 344.0 134.0 — 108 67.7 1630.0 347.0 140.0 —

[0270] TABLE 16 Example 10 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 4 40.9 231.0 25.9 10.5 4.5 7 42.4 174.0 34.9 12.7 3.7 1546.2 318.0 61.6 24.6 6.4 18 47.7 307.0 80.3 32.1 7.7 26 51.7 604.0 136.054.9 11.1 32 54.7 1360.0 239.0 70.2 9.5 37 57.3 2200.0 354.0 71.3 8.0 4360.4 9600.0 1040.0 — — 50 64.2 21100.0 2220.0 650.0 — 55 66.9 43500.08390.0 1700.0 —

[0271] TABLE 17 Example 11 Shear rate Shear rate Shear rate Shear rateCalculated 0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculatedviscosity viscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa ·s) (Pa · s) (Pa · s) 3 43.64 27.6 9.2 3.7 2.0 9 45.57 32.0 17.4 5.5 2.813 46.91 72.0 21.8 7.1 3.9 19 48.99 59.0 19.3 7.8 4.4 25 51.17 111.034.1 13.4 6.2 31 53.44 201.0 48.3 19.8 7.7 36 55.41 358.0 72.9 26.9 9.144 58.69 695.0 134.0 37.2 — 49 60.82 911.0 176.0 45.5 — 54 63.02 1960.0338.0 — — 61 66.21 5150.0 768.0 — —

[0272] TABLE 18 Example 12 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 6 47.9 99.1 33.7 18.6 9.7 11 51.0 162.0 49.7 25.7 12.3 1352.2 234.0 57.7 28.8 11.9 19 55.8 426.0 76.2 33.4 13.7 28 61.0 588.0107.0 40.1 14.1 38 66.5 2620.0 316.0 63.5 12.1 44 69.6 13600.0 1500.0 —— 46 70.6 14100.0 1200.0 1510.0 51.3 53 74.1 54900.0 4740.0 152.0 118.058 76.5 70900.0 6040.0 617.0 177.0

[0273] TABLE 19 Example 13 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 2 55.35 13.90 13.00 10.40 3.21 7 57.43 55.10 24.60 15.904.52 14 60.62 92.90 41.70 24.50 — 18 62.60 170.00 36.90 27.70 7.50 2566.32 233.00 63.40 42.60 11.40 30 69.18 481.00 85.10 54.50 15.20 3773.47 868.00 152.00 75.10 41.10 41 76.07 1890.00 288.00 97.80 — 47 80.183310.00 463.00 107.00 — 51 83.05 17000.00 2010.00 264.00 —

[0274] TABLE 20 Example 14 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 2.00 56.57 33.80 11.90 5.66 6.26 7.50 59.61 44.40 15.30 7.534.42 14.50 63.48 97.20 20.30 9.84 6.30 19.50 66.24 87.70 27.70 13.107.49 25.00 69.28 634.00 31.30 16.30 8.93 30.00 72.04 584.00 49.20 26.3013.10 37.00 75.90 982.00 80.90 33.00 15.30 42.50 78.94 2410.00 218.0051.90 — 49.00 82.53 3240.00 208.00 65.20 23.90

[0275] TABLE 21 Example 15 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityViscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 1.00 45.34 94.90 43.10 24.00 — 1.00 45.34 135.00 54.30 28.005.51 10.50 48.94 183.00 84.70 48.80 10.20 14.50 50.70 249.00 119.0067.60 13.10 20.00 53.36 285.00 140.00 81.90 — 24.00 55.46 470.00 219.00107.00 — 28.50 58.00 612.00 277.00 132.00 — 35.00 61.98 1020.00 448.00178.00 — 38.50 64.29 1250.00 434.00 — — 41.50 66.35 2020.00 805.00 — —47.00 70.34 2210.00 867.00 — — 51.00 73.41 4620.00 1250.00 — — 55.0076.63 5760.00 1550.00 — — 61.00 81.73 17300.00 — — —

[0276] TABLE 22 Example 16 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 2.00 56.54 — 30.20 10.90 4.11 6.00 58.39 213.00 41.40 13.904.73 12.00 61.07 347.00 49.60 15.00 5.59 16.50 63.02 371.00 58.20 15.906.33 21.50 65.10 630.00 105.00 25.40 8.83 26.00 66.92 689.00 115.0027.60 — 32.00 69.24 975.00 177.00 35.80 9.42 36.00 70.73 — 227.00 54.50— 43.00 73.22 1310.00 202.00 56.80 — 49.00 75.24 1640.00 213.00 — —55.00 77.15 3550.00 433.00 101.00 — 60.00 78.66 6680.00 — — — 66.0080.37 85400.00 — — —

[0277] TABLE 23 Example 17 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 2 42.43 55.00 26.10 16.40 3.64 6 43.93 76.50 35.50 19.104.03 10 45.16 98.70 45.70 24.90 5.26 15 46.93 126.00 60.30 32.90 7.19 2048.69 156.00 76.90 41.30 8.60 25 50.76 210.00 102.00 53.70 7.31 30 53.01210.00 132.00 73.00 14.50 35 55.37 257.00 129.00 96.30 17.60 40 57.64 —206.00 127.00 10.80 45 60.32 593.00 340.00 138.00 8.50 50 63.27 1160.00489.00 184.00 9.19 55 66.53 2350.00 686.00 257.00 3.66 60 70.14 2740.00920.00 244.00 33.50 65 73.99 9100.00 1300.00 302.00 48.40

[0278] TABLE 24 Example C18 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated Viscosityviscosity viscosity viscosity (min) Solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 3.0 41.74 506 104 16 3 9.0 46.28 1465 341 59 13 14.5 50.995043 1334 305 51 23.0 59.16 16240 5356 910 193 29.0 65.50 22290 127502040 448

[0279] TABLE 25 Example C19 Shear rate Shear rate Shear rate Shear rate0.0997 s⁻¹ 0.990 s⁻¹ 9.97 s⁻¹ 78.6 s⁻¹ Time Calculated viscosityviscosity viscosity viscosity (min) Solids (%) (Pa · s) (Pa · s) (Pa ·s) (Pa · s) 0. 22.20 68 28 10 3 5.0 24.03 120 56 18 4 12.0 26.54 1156422 82 15 18.0 28.93 5804 1588 212 33 24.0 31.81 8118 2073 289 69 31.036.13 12560 4273 568 116 38.0 41.88 12720 3278 415 78 44.0 48.27 330208738 1087 186

1. An aqueous coating composition comprising a crosslinkablewater-dispersible polyester oligomer(s) wherein said composition whendrying to form a coating has the following properties: i) an open timeof at least 20 minutes; ii) a wet edge time of at least 10 minutes; iii)a thumb hard time of ≦48 hours; iv) a tack-free time of ≦20 hours; v) 0to 25% of co-solvent by weight of the composition; and vi) anequilibrium viscosity of ≦5,000 Pa.s, at any solids content when dryingin the range of from 20 to 55% by weight of the composition, using anyshear rate in the range of from 9±0.5 to 90±5 s⁻¹ and at 23±2° C.
 2. Anaqueous coating composition according to claim 1 wherein said polyesteroligomer(s) has a solution viscosity ≦150 Pa.s, as determined from a 80%by weight solids solution of the crosslinkable polyester oligomer(s) inat least one of the solvents selected from the group consisting ofN-methylpyrrolidone, n-butylglycol and mixtures thereof, using a shearrate of 90±5 s⁻¹ and at 50±2° C.
 3. An aqueous coating compositionaccording to claim 1 wherein said polyester oligomer(s) has a solutionviscosity ≦250 Pa.s, as determined from a 70% by weight solids solutionof the crosslinkable polyester oligomer(s) in a solvent mixtureconsisting of: i) at least one of the solvents selected from the groupconsisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof;ii) water and iii) N,N-dimethylethanolamine; where i), ii) and iii) arein weight ratios of 20/7/3 respectively, using a shear rate of 90±5 s⁻¹and at 23±2° C.
 4. An aqueous coating composition comprising acrosslinkable water-dispersible polyester oligomer(s) wherein saidcomposition when drying to form a coating has the following properties:i) an open time of at least 20 minutes; ii) a wet edge time of at least10 minutes; iii) a thumb hard time of ≦48 hours; iv) a tack-free time of≦20 hours; v) 0 to 25% of co-solvent by weight of the composition; vi)an equilibrium viscosity of ≦5,000 Pa.s, at any solids content whendrying in the range of from 20 to 55% by weight of the composition,using any shear rate in the range of from 9±0.5 to 90±5 s⁻¹ and at 23±2°C.; and vii) wherein said polyester oligomer(s) has a solution viscosity≦250 Pa.s, as determined from a 70% by weight solids solution of thecrosslinkable polyester oligomer(s) in a solvent mixture consisting of:a) at least one of the solvents selected from the group consisting ofN-methylpyrrolidone, n-butylglycol and mixtures thereof; b) water and c)N,N-dimethylethanolamine; where a), b) and c) are in weight ratios of20/7/3 respectively, using a shear rate of 90±5 s⁻¹ and at 23±2° C. 5.An aqueous composition according to any one of the preceding claimswherein said composition has an equilibrium viscosity ≦5,000 Pa.s whenmeasured using any shear rate in the range of from 0.09±0.005 to 90±5s³¹¹, and an equilibrium viscosity of ≦3,000 Pa.s when measured using anyshear rate in the range of from 0.9±0.05 to 90±5s³¹ ¹, and anequilibrium viscosity of ≦1,500 Pa.s when measured using any shear ratein the range of from 9±0.5 to 90±5s⁻¹, at any solids content when dryingin the range of from 20 to 55% by weight of the composition and at 23±2°C.
 6. An aqueous composition according to any one of the precedingclaims wherein said composition has an equilibrium viscosity ≦5,000 Pa.swhen measured using a shear rate in the range of from 0.09±0.005 to90±5s⁻¹ after a 12% increase of the solids content by weight of thecomposition when drying.
 7. An aqueous composition according to any oneof the preceding claims wherein the crosslinkable polyester oligomer(s)has a measured weight average molecular weight in the range of from1,000 to 100,000 Daltons.
 8. An aqueous composition according to any oneof the preceding claims wherein the crosslinkable polyester oligomer(s)has a PDi≦30.
 9. An aqueous composition according to any one of thepreceding claims wherein the crosslinkable polyester oligomer(s) has ameasured Tg in the range of from −90 to 100° C.
 10. An aqueouscomposition according to any one of the preceding claims wherein thecrosslinkable water-dispersible polyester oligomer(s) isself-crosslinkable.
 11. An aqueous composition according to any one ofthe preceding claims wherein the crosslinkable water-dispersiblepolyester oligomer(s) is crosslinkable by autoxidation optionally incombination with Schiff base crosslinking.
 12. An aqueous compositionaccording to claim 11 wherein the crosslinkable water-dispersiblepolyester oligomer(s) contains autoxidisable groups and carbonylfunctional groups.
 13. An aqueous composition according to any one ofclaims 1 to 10 wherein the crosslinkable water-dispersible polyesteroligomer(s) is crosslinkable by Schiff base crosslinking optionally incombination with silane condensation.
 14. An aqueous compositionaccording to any one of claims 1 to 10 wherein the crosslinkablewater-dispersible polyester oligomer(s) is crosslinkable by silanecondensation optionally in combination with autoxidation.
 15. An aqueouscomposition according to any one of the preceding claims additionallycomprising a dispersed polymer(s).
 16. An aqueous composition accordingto claim 15 wherein the dispersed polymer(s) has a measured weightaverage molecular weight ≧120,000 Daltons.
 17. An aqueous compositionaccording to claim 15 wherein the dispersed polymer(s) has a measuredweight average molecular weight <120,000 Daltons with the proviso thatthe dispersed polymer(s) has a solution viscosity >150 Pa.s, asdetermined from a 80% by weight solids solution of the dispersedpolymer(s) in at least one of the solvents selected from the groupconsisting of N-methylpyrrolidone, n-butylglycol and mixtures thereof,using a shear rate of 90±5 s⁻¹ and at 50±2° C.
 18. An aqueouscomposition according to any one of claims 15 to 17 wherein thedispersed polymer(s) has particle size in the range of from 25 to 1000nm.
 19. An aqueous composition according to any one of claims 15 to 18wherein the dispersed polymer(s) has an acid value below 150 mgKOH/g.20. An aqueous composition according to any one of claims 15 to 19wherein the dispersed polymer(s) is a vinyl polymer.
 21. An aqueouscomposition according to claim 20 wherein the dispersed polymer(s) has ameasured Tg in the range of from −50 to 300° C.
 22. An aqueous coatingcomposition according to any one of the preceding claims comprising: i)0 to 15% co-solvent by weight of crosslinkable oligomer(s),non-crosslinkable oligomer(s) and dispersed polymer(s); ii) 35 to 65% ofoligomer by weight of crosslinkable oligomer(s), non-crosslinkableoligomer(s) and dispersed polymer(s); wherein the crosslinkablepolyester oligomer(s) comprises 45 to 75 wt % of fatty acid groups; andwherein the dispersed polymer(s) has an acid value below 20 mgKOH/g. 23.An aqueous coating composition according to any one of the precedingclaims comprising: i) 3 to 26% of a crosslinkable oligomer(s) by weightof the composition of which at least 52 wt % is said crosslinkablewater-dispersible polyester oligomer(s); ii) 0 to 6.5% of anon-crosslinkable oligomer(s) by weight of the composition; iii) 10 to56% of dispersed polymer(s) by weight of the composition; iv) 0 to 15%of co-solvent by weight of the composition; v) 5 to 65% of water byweight of the composition; where i)+ii)+iii)+iv)+v)=100%.
 24. An aqueouscoating composition according to any one of the preceding claimscomprising: i) 14 to 40% of a crosslinkable oligomer(s) by weight ofcrosslinkable ofigomer(s), non-crosslinkable oligomer(s) and dispersedpolymer(s) of which at least 52 wt % is said crosslinkable polyesteroligomer(s); ii) 0 to 10% of a non-crosslinkable oligomer(s) by weightof crosslinkable oligomer(s), non-crosslinkable oligomer(s) anddispersed polymer(s); iii) 50 to 85% of dispersed polymer(s) by weightof crosslinkable oligomer(s), non-crosslinkable oligomer(s) anddispersed polymer(s); where i)+ii)+iii)=100%.
 25. An aqueous coatingcomposition according to any one of the preceding claims additionallycomprising a pigment.
 26. A coating obtainable from an aqueouscomposition according to any one of the preceding claims.